350-401 Exam Questions and Answers

A network engineer is designing a campus network with high availability for critical services. Which Cisco technology enables traffic to be forwarded to an alternate next hop in the event of a first-hop router failure, without requiring any configuration changes on the hosts?

A company is deploying a wireless network in an office with high client density. Which Cisco architecture is best suited to handle client roaming without requiring a central controller for every roaming event?

An enterprise is using OSPF in a multi-area design. Area 1 is a regular area, and Area 2 is a totally stubby area. Which LSA types are present in Area 2?

A network engineer is troubleshooting a routing loop in an EIGRP network. Which mechanism is designed to prevent routing loops by causing a router to reject routes that are learned from a neighbor that is not the successor?

A company is implementing QoS in a network where voice traffic must have strict priority over all other traffic. Which queuing mechanism should be used on the outbound interface of a router to ensure voice packets are always sent first?

A network administrator is configuring a new VLAN 100 on a switch and wants to ensure that the VLAN is created and active. Which command is required to create a VLAN in the VLAN database?

A large enterprise is redesigning its campus network to support 5000 users across three buildings. The design must provide high availability and fast convergence in case of a link failure. The network engineer is considering using Spanning Tree Protocol (STP) in the access layer. What is the primary design concern with using STP in this scenario?

A company is deploying a new data center and needs to choose between a three-tier (core, aggregation, access) and a spine-leaf architecture. The network engineer is concerned about east-west traffic patterns for server virtualization. Which architecture is most suitable and why?

An enterprise network is experiencing high CPU utilization on the distribution layer switches. The design uses VLANs with SVIs for inter-VLAN routing, and HSRP for first-hop redundancy. The engineer notices that the standby switch is also experiencing high CPU. What is the most likely cause?

A network engineer is designing a WAN connection for a branch office that requires high availability and bandwidth aggregation. The branch has two internet connections from different ISPs. The engineer wants to use both links actively for load balancing and failover. Which design approach should be used?

A campus network uses a collapsed core design with two distribution switches and multiple access switches. The engineer wants to ensure that if one distribution switch fails, the access switches can still reach the core. The access switches are connected to both distribution switches. What additional configuration is required on the access switches?

An enterprise is migrating from a traditional three-tier campus design to a software-defined access (SD-Access) fabric. The engineer needs to ensure that the existing wireless infrastructure integrates seamlessly. Which component of SD-Access is responsible for integrating wireless and wired policies?

A network engineer is deploying Cisco SD-Access in a large enterprise campus. The design requires that all user traffic be segmented by Virtual Network (VN) and that the fabric edge nodes perform SGT-based enforcement. The engineer notices that traffic between two endpoints in the same IP subnet but different VNs is being forwarded directly at the fabric edge without any SGT inspection. What is the most likely cause?

An enterprise is migrating from a traditional three-tier campus network to Cisco SD-Access. The network engineer has deployed a fabric with a single fabric edge node and a single control plane node. Users in VLAN 10 report that they cannot reach the default gateway, which is a virtual IP on the fabric edge. The fabric edge is configured with a VLAN 10 SVI and the anycast gateway feature is enabled. What is the most likely cause of the problem?

A network architect is designing an SD-Access fabric for a large enterprise campus. The design must support segmentation at Layer 2 and Layer 3 across the fabric, using a centralized control plane and policy enforcement. Which two protocols are essential for the SD-Access overlay to meet these requirements?

An architect is planning a Cisco SD-Access fabric deployment. The design must support host mobility across multiple fabric edge nodes while ensuring consistent policy enforcement. Which fabric component is responsible for tracking endpoint locations and mapping them to the fabric?

A company is deploying an SD-Access fabric with multiple sites connected via a WAN. The design must allow inter-site traffic to be forwarded without requiring a full mesh of VXLAN tunnels between all edge nodes. Which fabric role should be used to interconnect the sites?

An architect is designing an SD-Access fabric for a campus network that requires segmentation of guest, employee, and IoT traffic. The design must use Cisco TrustSec for policy enforcement. Which component is responsible for assigning the Security Group Tag (SGT) to endpoints upon authentication?

A network engineer is deploying a Cisco SD-WAN solution for a global enterprise with multiple regional hubs. The engineer wants to ensure that traffic from branch offices to the internet is always forwarded directly from the branch, even if the branch has a primary MPLS link and a backup broadband link. The engineer configures the vSmart policy to direct internet-bound traffic to use the local exit at the branch. However, after deployment, the engineer notices that some internet traffic is still being sent to the regional hub before reaching the internet. What is the most likely cause of this behavior?

An enterprise is migrating from a traditional MPLS WAN to Cisco SD-WAN. The network team has deployed vEdge routers at all branch offices and a vSmart controller in the data center. The engineer configures a centralized control policy to influence path selection based on cost and latency. After the policy is activated, the engineer notices that some branches are not receiving the updated policy and are still using the default best-path selection. The vSmart is reachable from all branches, and the vEdge routers show that they are connected to the vSmart. What is the most likely reason for this issue?

A network engineer is configuring a Cisco SD-WAN fabric with vManage, vSmart, and vBond controllers. The engineer wants to ensure that all branch routers automatically discover the vSmart and vBond controllers without manual configuration on each branch. The engineer has configured the vBond with a public IP address and enabled NAT traversal. However, branch routers are failing to establish control connections. The engineer verifies that the branch routers have the correct organization name and that the vBond is reachable from the branches. What is the most likely missing configuration?

A large enterprise uses Cisco SD-WAN with multiple transport clouds (MPLS and Internet). The network team wants to ensure that voice traffic between two branch offices always uses the MPLS link, even if the Internet link has lower latency. The engineer creates a centralized data policy on the vSmart to match voice traffic based on DSCP EF and sets the preferred color to 'mpls'. After applying the policy, the engineer tests and finds that voice traffic is still using the Internet link. The vEdge routers show that the policy is received and active. What is the most likely reason for this failure?

A network engineer is troubleshooting a Cisco SD-WAN deployment where a branch office has two WAN links: a primary MPLS link and a backup LTE link. The engineer wants to configure application-aware routing so that critical applications (e.g., Salesforce) always use the MPLS link as long as its loss is below 2% and latency below 150 ms. The engineer configures an app-route policy on the vSmart with the appropriate SLA requirements. After deployment, the engineer notices that Salesforce traffic is still using the LTE link even when the MPLS link meets the SLA. What is the most likely cause?

An enterprise is deploying Cisco SD-WAN with a hub-and-spoke topology. The hub site has a vSmart controller and a vEdge router. The branch sites have vEdge routers. The engineer wants to ensure that all inter-branch traffic goes through the hub for security inspection. The engineer configures a centralized control policy on the vSmart to set the 'hub' as the preferred path for all routes. After the policy is applied, the engineer notices that branch-to-branch traffic is still going directly, bypassing the hub. The vEdge routers show that the control policy is received. What is the most likely issue?

A network engineer is configuring QoS on a Cisco Catalyst 9300 switch to prioritize voice traffic. The switch has multiple access ports connected to IP phones and PCs. The engineer applies a policy-map that matches DSCP EF and sets the CoS to 5. However, after testing, the voice packets are not being marked correctly. What is the most likely cause?

An enterprise is deploying a new VoIP system and wants to ensure voice traffic receives priority over data traffic on a WAN link. The engineer configures a class-map to match RTP traffic using the 'match protocol rtp' command. However, the class-map does not match any packets. What is the most likely reason?

A network engineer is designing a QoS policy for a Cisco router that connects to an MPLS VPN. The service provider expects all traffic to be marked with IP Precedence values. The engineer wants to ensure that voice traffic (DSCP EF) is mapped to IP Precedence 5. What configuration is required on the router to perform this mapping?

A company is implementing QoS on its campus network. The network engineer configures a policy-map that sets the CoS value for voice traffic to 5 on a switch interface. However, when the traffic reaches the router, the CoS marking is lost. What is the most likely reason?

A network engineer is troubleshooting voice quality issues on a WAN link. The engineer notices that voice packets are being dropped during congestion. The QoS policy uses LLQ for voice traffic, but the priority queue is not providing the expected bandwidth. What is the most likely cause?

An enterprise is deploying QoS across a network that includes both Cisco and non-Cisco devices. The engineer wants to use a marking scheme that is end-to-end and not stripped at Layer 3 boundaries. Which marking field should the engineer use?

A network engineer is troubleshooting a Cisco IOS-XE router that hosts multiple virtual routing and forwarding (VRF) instances. Users in VRF-A report they cannot reach a server in VRF-B. The engineer verifies that both VRFs have the correct routes and that the router has a route leaking configuration using route-target import/export. However, connectivity still fails. What is the most likely cause?

A data center uses Cisco Nexus 9000 switches with VXLAN EVPN to provide network virtualization. The operations team notices that VLAN 100 (mapped to VNI 10100) is not reachable across the fabric, although other VLANs work fine. The NVE interface is up, and the EVPN address-family is configured. Which two actions should the engineer take to isolate the issue?

A network engineer is deploying a Cisco Catalyst 9300 switch as a virtual switch using StackWise Virtual. The switch will connect to two upstream routers for redundancy. What is the best practice for connecting the uplinks?

A cloud provider uses Cisco ACI to automate provisioning of tenant networks. A new tenant requires a Layer 2 bridge domain that extends to an external Layer 2 network via a VPC. The engineer creates a bridge domain with the settings: Type: Regular, L2 Unknown Unicast: Flood, L3 Unknown Multicast Flood: Flood, and Multi-Destination Flooding: Flood. The VPC is configured as a virtual port channel. The tenant reports that broadcast traffic is not reaching the external network. What is the most likely cause?

An enterprise uses VMware vSphere to host multiple virtual machines (VMs). The network team wants to implement a virtual firewall on the hypervisor to inspect traffic between VMs on the same ESXi host. Which technology should be used?

A network engineer configured three interfaces on a switch as shown. A host connected to Ethernet1/2 sends an untagged frame. Which VLAN will this frame be placed into when it reaches Ethernet1/3?

A company is migrating its legacy firewall services to a virtualized environment using Cisco NFV. The network engineer deploys a virtual firewall (vFW) on an NFVIS-enabled UCS platform. After the deployment, traffic through the vFW is intermittent and performance monitoring shows high CPU usage on the host. Which action should the engineer take to improve performance?

An enterprise is deploying a virtual router (vRouter) as part of its NFV infrastructure. The engineer needs to ensure that the vRouter can handle a sudden spike in traffic without dropping packets. The vRouter is running on a KVM hypervisor. What should the engineer configure to guarantee CPU resources for the vRouter during peak demand?

A network engineer is deploying a virtual WAN edge device using Cisco SD-WAN on an NFVIS platform. After powering on the VM, the device fails to boot and the NFVIS console shows 'ERROR: No bootable device found'. The engineer verified that the ISO image is correctly uploaded. What is the most likely cause?

An engineer is managing a Cisco NFVIS host running multiple virtual network functions (VNFs). The engineer needs to upgrade the NFVIS software to a new version that includes critical security patches. The upgrade process must minimize downtime. Which upgrade method should the engineer use?

A company uses Cisco NFVIS to host a virtual ASA (vASA) and a virtual router (vRouter). The engineer notices that the vASA cannot communicate with the vRouter even though both are on the same NFVIS host. The vASA is connected to a bridge network, and the vRouter is connected to a different bridge. What should the engineer do to enable communication between the two VNFs?

An engineer is deploying a virtual network function (VNF) on a Cisco NFVIS host. The VNF requires four virtual NICs, each connected to a different network segment. The engineer creates four bridges on NFVIS and attaches each vNIC to a separate bridge. After deployment, the VNF can only communicate on the first bridge. What is the most likely cause?

A network engineer is deploying a new virtualized application on a VMware vSphere cluster. The application requires dedicated CPU cores to meet licensing requirements, and the engineer must ensure that no other virtual machine can use those cores. The cluster uses VMware ESXi 7.0. Which configuration should the engineer apply to the virtual machine?

An enterprise is migrating a legacy application from a physical server to a virtual machine on a KVM-based hypervisor. The application requires direct access to a PCIe network interface card for performance reasons. The engineer needs to provide the VM with dedicated hardware access while maintaining isolation from other VMs. Which technology should the engineer use?

A network engineer is troubleshooting performance issues on a VMware ESXi host running multiple VMs. The host has two physical CPUs, each with 8 cores (16 logical processors with Hyper-Threading enabled). One VM, configured with 8 vCPUs, experiences high CPU ready time. Other VMs on the host are idle. What is the most likely cause of the high CPU ready time?

A company is deploying a virtualized firewall on a VMware ESXi host. The firewall VM requires high network throughput and low latency. The engineer decides to use SR-IOV to assign a virtual function (VF) from a physical NIC to the VM. After configuration, the VM can communicate, but the host's management network becomes unreachable. What is the most likely cause?

A network engineer is designing a disaster recovery solution using VMware vSphere. The engineer needs to replicate virtual machines from the primary site to a secondary site with minimal downtime. The application VMs are running on NFS datastores. The engineer plans to use vSphere Replication. What prerequisite must be met for vSphere Replication to work with NFS datastores?

An engineer is deploying a Linux virtual machine on a KVM hypervisor. The VM needs to be connected to a virtual network that provides isolation from other VMs on the same host but allows communication with the host and external networks. The engineer creates a Linux bridge and attaches the VM's tap interface to it. However, the VM cannot reach the external network. The host has a physical NIC (eth0) connected to the corporate network. What is the missing configuration step?

A network engineer is configuring MPLS L3VPN on a Cisco IOS-XE PE router. The engineer creates a VRF named CUSTOMER_A with route-target import and export 100:1. After configuring the VRF on the interface connected to the CE router, the CE router can ping the PE's VRF interface IP, but cannot reach any remote VPNv4 routes. The BGP session between PE and route reflector is up. What is the most likely cause?

An enterprise uses VRF-lite to isolate guest Wi-Fi traffic from corporate traffic on a Cisco Catalyst 9300 switch. The guest VRF (GUEST) is configured on VLAN 100, and the corporate VRF (CORP) on VLAN 200. Both VRFs use the same default gateway router connected via a trunk. The engineer notices that guest devices can reach the internet but cannot access the guest captive portal hosted on a server in VLAN 100. The server's IP is reachable from the switch itself. What is the issue?

A service provider uses MPLS L3VPN with multiple VRFs on a Cisco ASR 1000 PE router. One customer VRF (RED) has overlapping IP addresses with another VRF (BLUE). The engineer configures route-target import/export as 100:1 for RED and 200:2 for BLUE. Both VRFs have a static default route pointing to the CE. The PE receives VPNv4 routes from the route reflector for both VRFs. However, traffic from RED to its CE is working, but traffic from BLUE to its CE is intermittently failing. What is the most likely cause?

A network engineer is troubleshooting a VRF-lite deployment on a Cisco Nexus 9000 switch. Two VRFs, PROD and DEV, are configured. The switch has an SVI for VLAN 10 in VRF PROD and VLAN 20 in VRF DEV. A firewall is connected to a Layer 3 port in VRF PROD for internet access. The engineer needs to allow the DEV VRF to reach the internet through the same firewall, but without using a separate physical interface. What should the engineer configure?

An engineer is configuring MPLS L3VPN on a Cisco IOS-XR router. The VRF CUSTOMER_B is configured with route-target import 100:1 and export 100:1. The engineer notices that the VRF routes are not being advertised to the route reflector. The BGP session to the route reflector is established and the VPNv4 address family is activated. What is the missing configuration?

A company uses VRF-lite to separate management traffic (VRF MGMT) from user traffic (VRF USER) on a Cisco Catalyst 3850 stack. The management network is 10.0.0.0/24, and the user network is 192.168.1.0/24. The engineer wants to allow SSH access from the user network to the management network for device administration. The switch has an SVI for each VRF. What is the simplest way to achieve this while maintaining VRF isolation?

A network engineer is troubleshooting an EIGRP adjacency issue between two routers. The engineer verifies that both routers have the same K-values and autonomous system number. However, the adjacency does not form. Which configuration issue is most likely the cause?

A company is implementing QoS in a campus network. Voice traffic must be prioritized over data traffic, and all traffic should be marked at Layer 2 and Layer 3. Which combination of marking values should be used on access ports to achieve this?

An engineer needs to configure a switchport to carry traffic for multiple VLANs to a router using a single physical link. Which configuration should be applied on the switchport?

A network engineer is deploying a new WLAN and needs to ensure that client traffic is encrypted using AES with a pre-shared key. Which security configuration should be applied to the wireless SSID?

A network administrator is troubleshooting an issue where OSPF routes are not being learned from a neighbor. The administrator checks the OSPF configuration and sees that both routers are in the same area. The neighbor state is stuck in EXSTART. What is the most likely cause?

An engineer is configuring a new VLAN 100 on a switch. Which command must be used to create the VLAN?

A network engineer is troubleshooting OSPF adjacency issues between two routers connected via a Gigabit Ethernet link. The engineer notices that the routers are stuck in the EXSTART state. Both routers have the same MTU of 1500 bytes. What is the most likely cause of this issue?

An enterprise network uses OSPF as its IGP. The network engineer notices that a particular route learned via OSPF is not being installed in the routing table, even though the neighbor adjacency is up and the route appears in the OSPF database. The route is an external route redistributed from EIGRP. What is the most likely cause?

A network engineer is configuring OSPF in a multi-area design. The engineer wants to reduce the amount of LSA flooding and the size of the LSDB in area 0. Which OSPF feature should be implemented on the ABR to achieve this goal?

A network engineer is troubleshooting an OSPF adjacency issue between two routers connected via a serial link. The adjacency is stuck in the INIT state. The engineer has verified that the IP addresses are in the same subnet and that the link is up. What is the most likely cause?

A network engineer is designing an OSPF network with multiple areas. The engineer wants to ensure that routers in area 2 can reach networks in area 0, but they should not learn any external routes from other ASs. Which OSPF area type should be configured for area 2?

A network engineer is troubleshooting an OSPF issue where a router is not learning a route to a network that is advertised via a type 5 LSA from an ASBR. The engineer checks the OSPF database and sees the type 5 LSA, but the route is not in the routing table. The forwarding address in the LSA is 0.0.0.0. What is the most likely cause?

An enterprise network has two routers, R1 and R2, both running BGP. R1 is an eBGP speaker with ISP1, and R2 is an eBGP speaker with ISP2. Both routers are in the same AS 65000. The engineer wants to ensure that traffic from the enterprise to the Internet prefers the path through ISP1 when both links are up. R1 learns a default route from ISP1, and R2 learns a default route from ISP2. Which BGP attribute should the engineer modify on R1 to influence outbound traffic selection?

A network engineer is troubleshooting BGP peering between two routers in different autonomous systems. The peering is established over a directly connected Ethernet link. The engineer notices that the BGP session is flapping every few minutes. The configuration on both routers appears correct, and the IP connectivity is stable. The engineer checks the BGP logs and sees messages like 'BGP-3-NOTIFICATION: sent 4/0 (Hold Timer Expired)'. What is the most likely cause of this issue?

A network engineer is configuring BGP on a Cisco router that is part of an enterprise network with multiple BGP peers. The router receives routes from two different ISPs. The engineer wants to ensure that only specific prefixes from ISP-A are installed in the routing table, while all other routes from ISP-A are ignored. Additionally, the engineer wants to accept all routes from ISP-B. Which BGP feature should be used on the router for the peering with ISP-A?

An enterprise has two BGP routers, R1 and R2, both in AS 65000. R1 peers with ISP1 (AS 100) and R2 peers with ISP2 (AS 200). The enterprise advertises a prefix 192.168.0.0/24 to both ISPs. The engineer wants to ensure that traffic from the Internet to this prefix enters the network primarily via R1, and only uses R2 if the link to ISP1 fails. Which BGP attribute should be manipulated on the updates sent to the ISPs?

A network engineer is configuring BGP on a Cisco router that connects to two ISPs. The router has a default route pointing to each ISP. The engineer wants to load balance outbound traffic across both ISPs. The router receives a default route from both ISPs. Which BGP configuration approach will allow the router to install both default routes in the routing table and load balance traffic?

An engineer is configuring BGP on a router that will act as a route reflector to reduce iBGP peering requirements. The router has several iBGP peers. The engineer wants to ensure that the route reflector does not modify the next-hop attribute of routes it reflects to its clients. Which configuration command should the engineer use?

A network engineer is troubleshooting an EIGRP issue in a large enterprise network. Two routers, R1 and R2, are connected via a T1 link. R1 is learning a route to 10.0.0.0/8 from R2 with a metric of 28160, but the same route is also learned from another neighbor with a metric of 26880. The engineer notices that the route from R2 is not being installed in the routing table. What is the most likely cause?

An engineer configures EIGRP on a new router in a DMVPN network. The router has a single physical interface with two subinterfaces: one for the DMVPN tunnel and one for a direct point-to-point link to a hub router. The engineer notices that EIGRP adjacencies form only on the point-to-point link, not on the DMVPN tunnel. The tunnel interface is configured with ip nhrp network-id 1 and ip nhrp nhs 10.1.1.1. What is the most likely reason?

A network engineer is designing an EIGRP network with multiple routers. The network has a core layer where all routers are fully meshed. The engineer wants to ensure that if a link fails, EIGRP converges quickly without relying on route redistribution or static routes. The engineer configures EIGRP with default timers. However, during a failure simulation, convergence takes over 15 seconds. What is the most likely reason?

An engineer is troubleshooting an EIGRP issue where a router is not learning a specific route from a neighbor. The engineer runs 'show ip eigrp topology all-links' and sees the route in the topology table with a feasible distance of 100 and a reported distance of 120. The neighbor's advertised distance is 80. The router's own computed distance to the network is 150. The route is not in the routing table. What is the most likely cause?

A network engineer is configuring EIGRP on a router that connects to multiple remote sites via Frame Relay. The engineer wants to ensure that EIGRP does not form adjacencies over the Frame Relay interfaces to reduce overhead, but still wants to advertise the connected networks. The engineer applies the 'passive-interface' command to the Frame Relay interfaces. However, the remote sites stop receiving the routes. What is the most likely reason?

An engineer is troubleshooting an EIGRP convergence issue in a network with redundant links. The engineer notices that when a primary link fails, the backup link takes over immediately, but the routing table shows the route with a higher metric. The engineer wants to ensure that the backup link is used only when the primary fails, and that traffic is not load-balanced. The engineer has configured 'variance 2' on all routers. What is the most likely effect of this configuration?

A network engineer is troubleshooting a connectivity issue between two switches, SW1 and SW2, connected via a trunk link. SW1 is a Cisco Catalyst 3850 running IOS-XE, and SW2 is a Cisco Catalyst 2960 running IOS. The trunk is configured as a dynamic desirable mode on SW1 and dynamic auto on SW2. The engineer notices that the trunk is not forming. What is the most likely cause?

An engineer is configuring a new access switch for a branch office. The switch must support multiple VLANs for different departments: VLAN 10 (Engineering), VLAN 20 (Sales), and VLAN 30 (Management). The uplink to the distribution switch is a trunk. The engineer wants to ensure that only the required VLANs are allowed on the trunk and that the native VLAN is changed from the default to VLAN 99 for security reasons. Which configuration commands should the engineer apply on the access switch's uplink interface?

A network engineer is deploying a new server farm with multiple servers connected to a Cisco Nexus 9000 switch. Each server is dual-homed to two separate access switches for redundancy. The servers are configured with NIC teaming in active-standby mode. The engineer wants to ensure that if the active link fails, traffic continues without interruption. The access switches are connected to each other via a trunk. Which technology should the engineer implement on the access switches to prevent loops and allow both uplinks to be active?

An engineer is troubleshooting a problem where a host in VLAN 20 cannot communicate with a host in VLAN 30, even though both are connected to the same access switch. The access switch is configured with VLANs 20 and 30, and the uplink to the distribution switch is a trunk that allows both VLANs. The distribution switch has SVIs for both VLANs and IP routing is enabled. The engineer verifies that the trunk is up and both VLANs are allowed. What is the most likely cause of the communication failure?

A network engineer is configuring a new Cisco Catalyst 9300 switch to connect to an existing network. The uplink to the core switch is configured as a trunk. The engineer wants to ensure that all VLANs except VLAN 1 are allowed on the trunk, and that the native VLAN is set to VLAN 999. Which configuration should the engineer apply on the uplink interface?

An engineer is troubleshooting a connectivity issue between two switches, SW1 and SW2, connected via a trunk. The trunk is configured with switchport mode trunk on both sides. The engineer notices that some VLANs are not passing traffic, even though they are in the allowed list. The output of 'show interfaces trunk' on SW1 shows that VLANs 10, 20, and 30 are in the allowed list and are active. However, hosts in VLAN 30 cannot reach the distribution switch. What is the most likely cause?

A network engineer is troubleshooting an STP issue in a switched network. The network has two distribution switches connected via a trunk, and each distribution switch connects to the same access switch. The engineer notices that the root bridge is not the intended distribution switch. Upon checking, the engineer sees that the access switch has a higher priority than the distribution switches. The engineer needs to ensure that the intended distribution switch becomes the root bridge without causing a temporary loop. What should the engineer do?

An engineer is designing a redundant Layer 2 network with multiple VLANs. The network uses Rapid PVST+ for STP. The engineer wants to ensure that different VLANs have different root bridges to optimize traffic flow. The distribution switches are Cisco Catalyst 9300s. The engineer has configured one distribution switch as the root for VLANs 10 and 20, and the other as the root for VLANs 30 and 40. However, after implementation, the engineer notices that all VLANs have the same root bridge. What is the most likely cause?

A network engineer is troubleshooting a Layer 2 loop issue. The network consists of three switches: SW1, SW2, and SW3, all connected in a triangle. The engineer notices that SW1 is the root bridge. After a link failure between SW1 and SW2, the network experiences a temporary loop. The engineer wants to prevent such loops in the future by enabling a feature that provides faster convergence and prevents temporary loops during topology changes. The engineer is using Rapid PVST+. Which feature should the engineer enable?

An engineer is configuring a new access switch that connects to two distribution switches via trunk links. The distribution switches are configured with Rapid PVST+ and are both running as root bridges for different VLANs. The engineer wants to ensure that the access switch does not become the root bridge for any VLAN, even if the distribution switches fail. The engineer also wants to prevent any unauthorized switch from becoming root. What configuration should the engineer apply on the access switch?

A network engineer is troubleshooting a connectivity issue in a switched network. The network uses Rapid PVST+ with multiple VLANs. The engineer notices that a host connected to an access port on SW1 cannot communicate with the default gateway, which is on a distribution switch. The access port is configured with PortFast and BPDU Guard. The engineer checks the switch logs and sees that the port went into errdisable state. What is the most likely cause of the errdisable state?

An engineer is designing a Layer 2 network with redundancy. The network uses MST (Multiple Spanning Tree) to reduce the number of STP instances. The engineer has configured two regions: Region 1 and Region 2. The engineer notices that switches in Region 1 are not forming a single MST region, and instead, they are treating each other as if they are in different regions. The engineer checks the configuration and finds that the region name and revision number are the same on all switches in Region 1, but the VLAN-to-instance mapping is different on one switch. What is the most likely cause of the issue?

A network engineer is configuring EtherChannel between two Cisco Catalyst switches. The ports are configured as access ports in VLAN 10. After configuring the port-channel interface and adding the physical ports, the engineer notices that the EtherChannel does not come up. The show etherchannel summary command shows the port-channel in a down state. What is the most likely cause?

An engineer is troubleshooting an EtherChannel between two switches. The show etherchannel summary output shows that the port-channel is up, but only one physical link is active. The other three links are in a suspended state. The physical ports are all configured identically with the same VLAN allowed. What is the most likely cause?

A network engineer is configuring an EtherChannel between a Cisco switch and a server that supports LACP. The switch ports are configured as trunk ports allowing multiple VLANs. The engineer wants to ensure the EtherChannel forms automatically without manual intervention. Which configuration should be applied on the switch?

A network engineer is troubleshooting an EtherChannel between two Cisco switches. The show etherchannel 1 port-channel command shows the port-channel is up, but traffic is not load-balanced evenly. The engineer notices that all traffic is using only one link. The physical ports are all configured identically. What is the most likely cause?

A network engineer is configuring EtherChannel between two Cisco switches using LACP. The engineer wants to ensure that if fewer than two links are operational, the EtherChannel does not come up. Which command should be configured?

A network engineer is configuring an EtherChannel between two Cisco switches. The engineer wants to use PAgP and ensure that the channel forms only if the neighboring switch is also configured for PAgP. Which mode should be configured on the local switch?

A network engineer is deploying a new wireless LAN controller (WLC) in a campus network. The WLC must manage 200 access points across three buildings. The engineer configures the WLC with a management IP address and enables CAPWAP. However, the access points fail to join the WLC. The APs are in the same VLAN as the WLC and can ping the WLC's management IP. What is the most likely cause of the APs not joining?

A company is deploying a new wireless network in a large warehouse. The network engineer must choose between using a centralized WLC architecture (with CAPWAP tunnels) or a converged access (SD-Access) wireless architecture. The warehouse has high-density client areas and requires low latency for real-time applications like voice and video. Which architecture should the engineer choose and why?

A network engineer is troubleshooting a wireless network where clients in a conference room experience intermittent connectivity. The engineer notices that the access point in that room is showing a high number of CRC errors on its uplink interface. The AP is connected to a Cisco 9300 switch via a copper cable. What is the most likely cause of the CRC errors?

An engineer is configuring a new Cisco 9800 WLC in a branch office. The WLC will manage 50 APs and must provide guest access with a captive portal. The engineer configures a guest SSID with open authentication and a redirect ACL for the captive portal. However, after the configuration, clients can associate to the guest SSID but cannot reach the captive portal page. What is the most likely cause?

A network engineer is deploying a wireless mesh network using outdoor access points. The mesh APs are configured to use 802.11a/n on the 5 GHz band for backhaul and 802.11b/g/n on the 2.4 GHz band for client access. The engineer notices that the mesh backhaul links are unstable and have high packet loss. What is the most likely cause of the instability?

An engineer is configuring a Cisco 9800 WLC for high availability using a pair of WLCs in an active/standby configuration. The engineer configures the same SSID and security settings on both WLCs. However, when the active WLC fails, clients that were connected to the active WLC do not automatically reconnect to the standby WLC. What is the most likely cause?

An engineer is troubleshooting an MPLS VPN where CE1 (10.1.1.0/24) cannot reach CE2 (10.2.2.0/24). The PE routers are running OSPF with the CE routers. On PE1, the 'show ip route vrf CUSTOMER' output shows 10.2.2.0/24 as an OSPF route, but the prefix is not present in the global BGP table. What is the most likely cause?

A service provider uses MPLS L3VPN with OSPF as the PE-CE routing protocol. A customer reports that a new subnet added on CE1 is not reachable from CE2, even though the PE1 router has the route in its VRF and BGP table. The 'show ip bgp vpnv4 vrf CUSTOMER' on PE2 shows the prefix with a valid next-hop. What should the engineer check next?

An engineer is designing an MPLS L3VPN service for a customer that requires overlapping IP addresses between two sites. The customer uses OSPF as the PE-CE protocol. The engineer configures VRFs on the PE routers and assigns unique route distinguishers (RDs) and route targets (RTs). However, the customer reports that routes from one site are not being installed in the other site's VRF. What is the most likely cause?

A network engineer is configuring MPLS TE (Traffic Engineering) in an MPLS core to optimize bandwidth utilization. After enabling MPLS TE on all core routers and configuring tunnels, the engineer notices that traffic is not being rerouted when a link fails. The 'show mpls traffic-eng tunnels' shows the tunnels are up but not using the backup path. What is the most likely missing configuration?

An enterprise is implementing MPLS L3VPN to connect multiple branch offices. The PE routers are using eBGP to exchange VPNv4 routes. The engineer notices that some VPN routes are not being advertised to the remote PE. The 'show bgp vpnv4 unicast all' on the local PE shows the routes as valid but not best. What is the most likely reason?

A network engineer is troubleshooting an MPLS L2VPN (VPWS) where two customer sites are connected via a pseudowire. The engineer has configured the xconnect on both PE routers, but the customer reports that the link is down. The 'show mpls l2transport vc' command on PE1 shows the VC state as 'down'. What is the most likely cause?

A network engineer is configuring a DMVPN Phase 3 deployment with EIGRP as the routing protocol. The hub router has multiple spoke routers behind a single physical interface. The engineer notices that spoke-to-spoke traffic is being forwarded through the hub instead of directly. The spoke routers have the correct NHRP and mGRE configuration. What is the most likely cause of this issue?

An enterprise is replacing its legacy Frame Relay WAN with MPLS L3VPN. The new MPLS provider assigns a single VRF to the customer. The customer's CE routers are running BGP with the provider's PE routers. The engineer notices that the CE routers can ping the PE loopback addresses but cannot reach remote CE loopbacks. The BGP sessions are established and routes are received. What is the most likely cause?

A network engineer is troubleshooting a site-to-site IPsec VPN tunnel between two Cisco routers. The tunnel is established and IKEv2 Phase 1 is up, but no traffic passes. The engineer checks the crypto map and sees that the ACL is configured to permit traffic between the two LAN subnets. However, 'show crypto ipsec sa' shows that the number of packets encapsulated and decapsulated is zero. What is the most likely cause?

An engineer is configuring a FlexVPN hub-and-spoke topology using IKEv2. The hub router is configured with a dynamic crypto map and a local pool for assigning IP addresses to spokes. The spokes are configured with a static crypto map and a tunnel interface with an IP address from the pool. The tunnel comes up, but the spoke cannot ping the hub's tunnel interface. The hub can ping the spoke's tunnel interface. What is the most likely cause?

A company is using a dual-homed MPLS L3VPN connection with two different ISPs. The CE router is running eBGP with both PE routers. The engineer wants to ensure that inbound traffic from the Internet to the company's web servers uses both links, but outbound traffic from the company should prefer ISP A. The company advertises the same /24 prefix to both ISPs. What BGP configuration should the engineer apply on the CE router?

An engineer is deploying a new SD-WAN solution using Cisco vManage. The WAN edge routers are connected to two different transport networks: MPLS and Internet. The engineer wants to ensure that voice traffic is always sent over the MPLS link when available, and only fails over to the Internet link if the MPLS link goes down. The engineer has configured a policy to set the preferred color for voice traffic to 'mpls'. However, during a test, voice traffic is still using the Internet link even though the MPLS link is up. What is the most likely cause?

A network engineer is configuring a Cisco router to provide internet access to a small office using a single public IP address assigned by the ISP. The engineer wants to allow internal hosts to initiate connections to the internet, but also needs to make a web server on the internal network reachable from the internet. The engineer configures a standard access list for NAT and an ip nat inside source list command. However, external users cannot reach the internal web server. What is the most likely cause?

A network engineer is troubleshooting a DHCP issue on a Cisco router configured as a DHCP server for a VLAN. Clients in the VLAN are able to obtain IP addresses from the DHCP server, but they are not receiving the correct DNS server address. The engineer checks the DHCP pool configuration and sees the dns-server command is configured with the correct IP address. What is the most likely cause of the problem?

A network engineer is configuring NAT overload (PAT) on a Cisco router to allow multiple internal hosts to share a single public IP address. The engineer uses the command ip nat inside source list 1 interface GigabitEthernet0/0 overload. After testing, internal hosts can access the internet, but some applications fail intermittently. The engineer suspects a NAT issue. What is the most likely cause?

A network engineer is configuring a Cisco router as a DHCP relay agent to forward DHCP requests from a client VLAN to a centralized DHCP server located in a different subnet. The engineer configures the ip helper-address command on the VLAN interface. However, clients in the VLAN are not receiving IP addresses. The DHCP server is reachable from the router. What is the most likely cause?

A network engineer is troubleshooting a NAT issue where an internal host cannot establish an SSH session to a remote server on the internet. The engineer checks the NAT translations on the border router and sees that the translation for the host's source IP is present. However, the SSH session times out. The engineer also notices that the remote server's IP is not in the NAT translation table. What is the most likely cause?

A network engineer is configuring a Cisco router to act as a DHCP server for a branch office. The engineer creates a DHCP pool for the 192.168.1.0/24 subnet and configures the default-router, dns-server, and domain-name options. However, clients are able to obtain IP addresses but cannot ping the default gateway. The engineer verifies that the router's interface IP is 192.168.1.1. What is the most likely cause?

A network engineer is troubleshooting multicast video distribution across an enterprise campus. The multicast source is connected to a switch that is the PIM Designated Router (DR) on a multi-access segment. Receivers in a different VLAN report that they are not receiving the multicast stream, although the DR shows the correct (S,G) entry. The engineer checks the RPF neighbor for the source and notices that the unicast route to the source points to a different interface than the one where the multicast stream is received. What is the most likely cause of the issue?

A network engineer is deploying IP multicast in an OSPF-based enterprise network. The network uses PIM sparse mode with a static RP. The engineer notices that multicast traffic from a source to a group is not reaching receivers in a remote subnet, even though the RP is reachable and the receivers have sent IGMP joins. The engineer checks the multicast routing table on the last-hop router and sees that the (S,G) entry is present, but the outgoing interface list (OIL) is empty. What is the most likely reason for the empty OIL?

An engineer is configuring multicast on a Cisco router running IOS-XE. The network uses PIM sparse mode with a static RP at 10.1.1.1. The engineer enters the command 'ip pim rp-address 10.1.1.1' but multicast traffic is not being forwarded. Upon verification, the engineer sees that the RP is reachable via OSPF, but the 'show ip pim rp mapping' command does not list any RP for the group. What is the most likely cause?

A network engineer is troubleshooting multicast connectivity in a large enterprise. The network uses PIM sparse mode with Auto-RP. The engineer notices that some routers are not receiving the RP mapping for a particular group. The engineer checks the Auto-RP mapping agent and sees that it is sending RP announcements, but the routers that are missing the mapping are not in the same PIM domain. What is the most likely reason?

An engineer is configuring multicast on a Cisco switch running IOS. The switch is acting as the IGMP querier for a VLAN. The engineer notices that multicast traffic is being flooded to all ports in the VLAN, even though only a few receivers have joined the group. The engineer checks the IGMP snooping configuration and sees that IGMP snooping is enabled globally and on the VLAN. What is the most likely cause of the flooding?

A network engineer is configuring PIM sparse mode in a network that uses a Bootstrap Router (BSR) for RP discovery. The engineer has configured a candidate BSR and candidate RPs. However, some routers in the network are not learning the RP set. The engineer checks the BSR and sees that it is receiving candidate RP advertisements, but the BSR messages are not being forwarded to all routers. What is the most likely cause?

A network engineer is configuring QoS on a Cisco Catalyst 3850 switch to prioritize voice traffic. The switch is connected to an IP phone and a PC using a single access port. The engineer applies a service policy on the access port that marks CoS 5 for voice and CoS 0 for data. However, the IP phone is not receiving any voice packets. What is the most likely cause?

An engineer is deploying QoS on a WAN link between two sites using a Cisco ISR 4451 router. The link is a 10 Mbps MPLS circuit. The engineer wants to ensure that voice traffic (EF) is never dropped, even during congestion. The current policy uses a single class map for voice with a policer that drops excess traffic. During peak hours, users report choppy voice calls. What change should the engineer make?

A network engineer is troubleshooting QoS on a Cisco Nexus 9000 switch. The switch is configured with a policy map that uses a class-default with a bandwidth remaining percent of 100. However, during congestion, traffic in a priority queue (class-map for EF) is experiencing drops even though the priority queue is not fully utilized. What is the most likely cause?

An engineer is configuring QoS on a Cisco ASR 1000 router to support three traffic classes: voice (EF), video (AF41), and data (default). The link is a 50 Mbps Ethernet circuit. The engineer wants to guarantee 10 Mbps for voice, 20 Mbps for video, and the remaining for data. The current policy uses bandwidth percent statements. During congestion, voice traffic is not receiving its guaranteed bandwidth. What is the most likely cause?

A network engineer is troubleshooting voice quality issues on a Cisco Catalyst 9300 switch. The switch is configured with auto QoS for voice, which enabled trust on the access ports. However, voice packets are being marked with DSCP EF but are still experiencing jitter. The engineer checks the interface queue statistics and sees that the priority queue is not being used. What is the most likely reason?

An engineer is configuring QoS on a Cisco ISR 4331 router for a site-to-site VPN tunnel. The tunnel interface is configured with a service policy that uses a class map matching DSCP EF. The engineer notices that the policy is not shaping traffic as expected; the tunnel bandwidth is 20 Mbps but the shaper is set to 10 Mbps. However, traffic still exceeds 10 Mbps. What is the most likely cause?

A network engineer notices intermittent connectivity issues between two switches connected via a trunk link. The trunk is configured with DTP in dynamic desirable mode on one side and trunk mode on the other. Which action should the engineer take to resolve the issue?

A network administrator is troubleshooting high CPU utilization on a Catalyst 9300 switch. The output of 'show processes cpu sorted' shows the 'IP Input' process consuming 45% CPU. Which tool should be used to identify the specific packets causing the issue?

A network engineer is implementing QoS on a WAN link to prioritize voice traffic. Which queuing mechanism provides the lowest latency for real-time traffic?

A network administrator is troubleshooting a BGP routing issue where routes from an eBGP neighbor are not being installed in the routing table. The 'show ip bgp' output shows the routes are received but not valid. What is the most likely cause?

A network engineer is designing a multicast network for IPTV. Which protocol is used by routers to discover which multicast groups are of interest to directly connected hosts?

Which TWO statements are true about IP SLA? (Choose two.)

A network engineer configures SNMPv2c on a Cisco router to monitor CPU and memory utilization. The NMS is reachable and configured with the same community string 'public'. However, the NMS receives no traps from the router. The engineer verifies that the router's SNMP configuration includes 'snmp-server enable traps' and 'snmp-server host 192.168.1.100 version 2c public'. What is the most likely cause of the missing traps?

An engineer is troubleshooting a syslog issue on a Cisco switch. The switch is configured with 'logging host 10.1.1.1' and 'logging trap informational'. The syslog server at 10.1.1.1 receives messages from other devices but not from this switch. The engineer can ping 10.1.1.1 from the switch. What is the most likely cause?

A network engineer configures SNMPv3 on a Cisco router for secure monitoring. The configuration includes 'snmp-server group ADMIN v3 priv', 'snmp-server user admin ADMIN v3 auth sha cisco123 priv aes 128 cisco456', and 'snmp-server host 10.1.1.2 version 3 priv admin'. The NMS is configured with the same credentials. However, the NMS cannot poll the router. The engineer verifies that the router's SNMP agent is enabled. What is the most likely cause?

An engineer notices that syslog messages from a Cisco router are not timestamped correctly. The router is configured with 'service timestamps log datetime msec' and 'logging host 10.1.1.1'. The syslog server shows messages with the correct time but the local logs on the router show incorrect timestamps. What is the most likely cause?

A network engineer configures SNMPv2c on a Cisco switch to send traps to an NMS at 192.168.1.100 with community 'monitor'. The engineer also configures 'snmp-server enable traps snmp linkdown linkup'. The NMS receives link traps but not authentication failure traps. The engineer has not configured any access control. What is the most likely reason?

An engineer is configuring syslog on a Cisco router to send messages to two servers: 10.1.1.1 (primary) and 10.1.1.2 (secondary). The configuration includes 'logging host 10.1.1.1' and 'logging host 10.1.1.2'. The engineer wants messages to be sent to both servers simultaneously. However, only the first server receives messages. What is the most likely cause?

A network engineer is troubleshooting intermittent packet loss on a WAN link connecting two data centers. The engineer suspects that certain traffic types are being dropped but needs to confirm this without impacting production. The engineer has access to Cisco IOS-XE routers at both ends. Which approach should the engineer use to identify the specific flows being dropped?

A large enterprise is migrating from traditional SNMP-based monitoring to streaming telemetry for better scalability and real-time visibility. The network team has Cisco Nexus 9000 switches running NX-OS. They want to stream interface counters and BGP neighbor state changes to a collector. Which telemetry technology should they implement?

A network engineer is configuring NetFlow on a Cisco ISR 4451 router to analyze traffic patterns. The engineer wants to export flow data to a collector every 60 seconds. After applying the configuration, the engineer notices that the export packets are not reaching the collector. The collector is reachable via ICMP. What is the most likely cause?

A service provider is using Cisco ASR 9000 routers and needs to collect NetFlow data from multiple customers' traffic. The engineer wants to ensure that flow records from different customers are not mixed and can be identified separately. The router supports Flexible NetFlow. What is the best approach?

A network operations center (NOC) is deploying streaming telemetry from Cisco IOS-XE devices to a Kafka-based analytics platform. The engineer needs to ensure that the telemetry data is encoded in a compact, efficient format for high-volume streaming. Which encoding format should the engineer configure?

A network engineer is troubleshooting a performance issue on a Cisco Catalyst 9300 switch. The engineer suspects that a specific application is using excessive bandwidth. The switch supports Flexible NetFlow. The engineer wants to monitor only the traffic from that application without affecting the switch's CPU. What is the most efficient way to configure this?

A network engineer is troubleshooting a performance issue between two hosts connected to a Cisco Catalyst 3850 switch. The engineer wants to capture all traffic sent and received by Host A (Gi1/0/1) and send it to a monitoring station connected to Gi1/0/24. The engineer configures 'monitor session 1 source interface Gi1/0/1 both' and 'monitor session 1 destination interface Gi1/0/24'. However, the monitoring station receives only traffic sent by Host A, not traffic received. What is the most likely cause?

A network engineer needs to monitor traffic between two VLANs on a Cisco Catalyst 9300 switch. The engineer wants to capture all packets that traverse the switch between VLAN 10 and VLAN 20. The monitoring station is connected to port Gi1/0/24. Which configuration should the engineer use to capture this inter-VLAN traffic?

An engineer is configuring RSPAN to monitor traffic from multiple switches in a data center. The monitoring station is connected to a central switch. The engineer has configured an RSPAN VLAN (VLAN 999) on all switches and set up the source sessions on the remote switches. However, the monitoring station receives no traffic. On the central switch, the engineer verifies that the RSPAN VLAN is active and that the destination session is configured. What is a likely missing configuration?

A network engineer is using a Cisco Catalyst 3850 switch to monitor traffic from a server connected to port Gi1/0/1. The monitoring station is on port Gi1/0/24. The engineer configures 'monitor session 1 source interface Gi1/0/1 both' and 'monitor session 1 destination interface Gi1/0/24'. The monitoring station receives traffic, but the engineer notices that the switch CPU utilization is high. What is the most likely cause of the high CPU?

A network engineer needs to monitor traffic from a specific VLAN (VLAN 100) on a Cisco Catalyst 9300 switch and send the mirrored traffic to a monitoring station on a different switch across a routed network. The engineer decides to use ERSPAN. Which configuration is required on the source switch?

An engineer is configuring SPAN on a Cisco Catalyst 3850 switch to monitor traffic from a trunk port (Gi1/0/1) that carries VLANs 10, 20, and 30. The monitoring station is on port Gi1/0/24. The engineer wants to capture only VLAN 20 traffic from the trunk. Which configuration should the engineer use?

A network engineer configures an IP SLA on a Cisco router to monitor reachability to a critical server at 10.1.1.1 using ICMP echo. The IP SLA is used as a track object for a static default route. After deployment, the engineer notices that the static route is never removed from the routing table, even when the server is unreachable. The IP SLA operation shows 'State: Active' and 'Latest RTT: NoConnection/Busy/Timeout'. What is the most likely cause?

An engineer configures IP SLA 100 to monitor the jitter and latency of a VoIP call path between two branch routers. The configuration uses UDP jitter with a target of 192.168.2.2 on port 16384. The engineer notices that the IP SLA operation shows 'State: Active' but no jitter or latency statistics are collected. The router is generating the probe packets, but the remote router does not respond. What is the most likely reason?

A network engineer configures IP SLA 1 to monitor HTTP server availability at 10.1.1.1 using HTTP GET. The operation is used as a track object for a backup static route. The engineer notices that the IP SLA operation shows 'State: Active' and 'Latest RTT: 200 ms', but the track object shows 'Track 1: up' even though the HTTP server returns a 404 error. What is the cause?

An engineer configures IP SLA 10 to monitor the reachability of a next-hop router at 10.1.1.1 using ICMP echo. The IP SLA is used as a track object for a static route. The engineer notices that the IP SLA operation shows 'State: Active' and 'Latest RTT: 1 ms', but the track object shows 'Track 10: up' even though the next-hop router is actually unreachable from the source. The source router has a default route pointing to 10.1.1.1. What is the most likely cause?

A network engineer configures IP SLA 20 to monitor the response time of a DNS server at 10.1.1.1 using DNS query for 'example.com'. The operation is used to influence routing decisions. The engineer notices that the IP SLA operation shows 'State: Active' and 'Latest RTT: 50 ms', but the DNS server is actually down and not responding to any queries. What is the most likely reason?

An engineer configures IP SLA 30 to monitor the one-way delay to a remote site using UDP jitter. The operation is used to adjust routing metrics via route maps. The engineer notices that the IP SLA operation shows 'State: Active' but the one-way delay values are inconsistent, sometimes showing negative values. What is the most likely cause?

A network engineer is configuring port security on a Cisco switch to prevent unauthorized devices from connecting. The requirement is to allow only the first two MAC addresses learned on an interface, and to disable the interface if a violation occurs. Which configuration achieves this?

An organization wants to implement 802.1X authentication on its wired network using Cisco ISE as the authentication server. The switches are configured with the necessary RADIUS settings. Which additional configuration is required on the switch interfaces to enable 802.1X?

A security engineer is configuring CoPP (Control Plane Policing) on a Cisco router to protect the control plane from DoS attacks. The policy must rate-limit SSH traffic to 1 Mbps with a burst of 2000 bytes, and drop all other traffic destined to the control plane that exceeds a default rate. Which class-map and policy-map configuration is correct?

A company has deployed a Cisco ASA firewall in transparent mode. The internal network uses VLAN 10 and the external network uses VLAN 20. The ASA is configured with two bridge groups: BVI 10 for inside and BVI 20 for outside. The security policy must allow HTTPS traffic from inside to outside. Which access-list entry is correct?

A network administrator is troubleshooting a DHCP snooping issue on a Cisco switch. The switch is configured with DHCP snooping globally and on VLAN 10. The trusted interface is GigabitEthernet0/1 connected to the DHCP server. However, clients on VLAN 10 are not receiving IP addresses from the DHCP server. What is the most likely cause?

Which TWO of the following are valid methods to mitigate VLAN hopping attacks?

A network engineer is configuring AAA on a Cisco ISR router to authenticate administrative users via a RADIUS server. The engineer configures the router with the command 'aaa new-model' and then 'aaa authentication login default group radius local'. When the engineer attempts to SSH to the router using a username that exists only on the RADIUS server, the authentication fails. The RADIUS server is reachable and the shared secret is correct. What is the most likely cause of the failure?

An enterprise network uses TACACS+ for device administration and RADIUS for network access (VPN and wireless). The TACACS+ server is configured to authorize commands. A network engineer notices that after a recent upgrade of the TACACS+ server software, some commands that were previously authorized are now being denied. The engineer checks the router configuration and sees 'aaa authorization commands 15 default group tacacs+'. The TACACS+ server logs show that the authorization requests are being sent and responded to. What is the most likely cause?

A network engineer is configuring a Cisco switch for 802.1X port-based authentication. The switch is configured with a RADIUS server for authentication. The engineer wants to allow devices that fail 802.1X authentication to still access a limited guest VLAN. The engineer configures 'authentication port-control auto' and 'authentication host-mode multi-host' on the interface. However, when a non-802.1X-capable device is connected, the port remains in the unauthorized state and does not fall into the guest VLAN. What is missing?

A company is deploying a new Cisco wireless LAN controller (WLC) and wants to use RADIUS for authenticating wireless users. The WLC is configured with the RADIUS server IP, shared secret, and authentication port 1812. However, users are unable to authenticate. The network engineer checks the RADIUS server logs and sees that the server is receiving authentication requests from the WLC but is responding with an 'Access-Reject' message. The WLC logs show 'RADIUS server not responding' for the same server. What is the most likely cause?

A network engineer is configuring a Cisco router to use TACACS+ for authentication and authorization of EXEC sessions. The engineer configures 'aaa new-model', 'aaa authentication login default group tacacs+ local', and 'aaa authorization exec default group tacacs+ local'. When a user tries to log in via SSH, the router prompts for username and password, but after entering correct credentials, the user is immediately disconnected. The TACACS+ server logs show that the authentication was successful. What is the most likely cause?

A network engineer is configuring a Cisco switch for 802.1X with RADIUS authentication. The switch is also configured with 'aaa authentication dot1x default group radius'. The engineer wants to use a single RADIUS server for both authentication and accounting. The RADIUS server is configured with the same shared secret for both services. The engineer configures 'radius-server host 10.1.1.1 auth-port 1812 acct-port 1813 key cisco123'. However, accounting records are not being sent to the server. The engineer verifies that the RADIUS server is reachable and that accounting is enabled on the server. What is the most likely cause?

A network engineer is troubleshooting an issue where SSH access to a Cisco router from a specific management subnet (10.10.10.0/24) is intermittently failing. The router has a CoPP policy applied to the control plane. The engineer checks the CoPP statistics and sees that packets from the management subnet are being dropped by the control-plane service-policy. Which configuration change should the engineer make to allow SSH from the management subnet while still protecting the control plane?

An enterprise network uses a Cisco Catalyst 9300 switch as a distribution layer device. The network team notices that ICMP echo requests from a monitoring server (192.168.1.100) to the switch's management IP are being dropped intermittently. The switch has a CoPP policy that includes a class-map matching ICMP traffic. The engineer checks the CoPP statistics and sees that ICMP packets from the monitoring server are being dropped by the policy. What is the most likely cause of this issue?

A network engineer is configuring CoPP on a Cisco ASR 1000 router to protect the control plane from excessive traffic. The engineer wants to allow BGP traffic from a specific peer (10.0.0.1) while rate-limiting all other BGP traffic. The engineer creates an ACL that permits TCP port 179 from host 10.0.0.1 and denies all other BGP traffic. The CoPP class-map matches this ACL. However, after applying the policy, BGP sessions from other peers are still being established. What is the most likely reason?

A network engineer is troubleshooting a connectivity issue between two VLANs on a Cisco Catalyst 3850 switch. The switch has an ACL applied to VLAN 10 that permits traffic from VLAN 20 to VLAN 10, but denies all other traffic. Hosts in VLAN 20 can ping hosts in VLAN 10, but not vice versa. The engineer checks the ACL and finds that it is applied inbound on VLAN 10. What is the most likely cause of the issue?

A network engineer is configuring CoPP on a Cisco Nexus 9000 switch to protect the control plane from a potential DoS attack. The engineer creates a class-map that matches traffic with a specific DSCP value (AF41) and applies a police rate of 10 Mbps. After applying the policy, the engineer notices that legitimate traffic with DSCP AF41 is being dropped even though the traffic rate is only 5 Mbps. What is the most likely cause?

A network engineer is troubleshooting an issue where a Cisco router is not responding to SNMP polls from a network management station (NMS) at 192.168.1.50. The router has a CoPP policy that includes a class-map matching SNMP traffic (UDP port 161). The engineer checks the CoPP statistics and sees that SNMP packets from the NMS are being dropped. The engineer wants to allow SNMP from the NMS while still protecting the control plane. Which configuration change should the engineer make?

A network engineer is deploying 802.1X on a Cisco switch for a mixed environment of Windows laptops and IP phones. The engineer configures the switchport with 'authentication port-control auto' and 'dot1x pae authenticator'. After connecting a Windows laptop, the switch logs show 'Authentication failed' for the laptop. The engineer verifies that the RADIUS server is reachable and the laptop's supplicant is configured correctly. What is the most likely cause of the authentication failure?

An enterprise is implementing Cisco TrustSec (CTS) to enforce role-based access control. The network engineer configures the switch with 'cts role-based enforcement' and 'cts manual' on an interface connecting to a trusted Cisco switch. The engineer also configures Security Group Tags (SGTs) on the RADIUS server. However, traffic between two hosts in different SGTs is not being filtered as expected. The engineer checks 'show cts role-based counters' and sees no drops. What is the most likely reason for the lack of enforcement?

A network engineer is configuring 802.1X on a Cisco Catalyst 9300 switch for a wired network. The engineer wants to allow devices that do not support 802.1X (e.g., printers) to still access the network using MAB (MAC Authentication Bypass). The engineer configures the interface with 'authentication port-control auto', 'dot1x pae authenticator', and 'mab'. However, after connecting a printer, the switch logs show 'MAB failed' repeatedly. The printer's MAC address is in the RADIUS server database. What is the most likely cause?

A network engineer is deploying Cisco TrustSec (CTS) with Security Group Access Control Lists (SGACLs) on a campus network. The engineer configures the switch with 'cts role-based enforcement' and assigns SGTs to users via 802.1X. The engineer tests connectivity between a user in SGT 10 and a server in SGT 20. The SGACL permits traffic from SGT 10 to SGT 20, but the user cannot reach the server. The engineer checks 'show cts role-based sgt map' and sees that the user's SGT is 0. What is the most likely cause?

An organization is implementing 802.1X for wireless users using Cisco ISE as the RADIUS server. The network engineer configures the wireless LAN controller (WLC) with 802.1X authentication. Users report that they can connect to the SSID but cannot access any network resources. The engineer checks the WLC and sees that users are authenticated and assigned to VLAN 100. The engineer also checks the switchport connecting the WLC and sees it is a trunk. What is the most likely issue?

A network engineer is configuring 802.1X on a Cisco switch for a voice VLAN deployment. The switchport is connected to an IP phone, which then connects to a PC. The engineer configures the interface with 'authentication port-control auto', 'dot1x pae authenticator', and 'switchport voice vlan 10'. The PC authenticates successfully, but the IP phone does not get an IP address from the voice VLAN. The engineer verifies that the phone is configured for 802.1X and the RADIUS server is correct. What is the most likely cause?

A network engineer is configuring a site-to-site IPsec VPN between two Cisco routers. The engineer wants to ensure that the VPN tunnel uses the strongest possible encryption and authentication algorithms. The engineer configures the following: crypto isakmp policy 10, authentication pre-share, encryption aes-256, group 14, lifetime 86400. On the remote router, the engineer configures: crypto isakmp policy 10, authentication pre-share, encryption aes-256, group 14, lifetime 86400. The tunnel fails to establish. What is the most likely cause?

A network engineer is tasked with deploying a DMVPN Phase 2 network for a company with multiple branch offices. The hub router is a Cisco 4451-X and the spoke routers are Cisco 4331s. After configuration, the spokes can ping the hub's tunnel IP, but cannot reach each other's tunnel IPs. The engineer checks the routing tables and sees that the hub has routes for both spoke subnets, but the spokes do not have routes to each other. What is the most likely cause?

An engineer is configuring a FlexVPN hub-and-spoke network. The hub router has a loopback0 with IP 10.0.0.1/32. The spokes are configured to use IKEv2 with certificates. The engineer notices that the spokes can establish the IKEv2 tunnel and can ping the hub's tunnel IP, but cannot reach the loopback0 address. The hub has a static route for the spoke subnets. What is the most likely issue?

A network engineer is configuring a GETVPN solution for a large enterprise with many remote sites. The engineer wants to ensure that all traffic between sites is encrypted using a common group key. The key server (KS) is a Cisco ASR 1000. After configuration, the group members (GMs) can register with the KS, but traffic between GMs is not encrypted. The engineer checks the KS configuration and sees that the crypto gdoi group has been defined with a transform set and a security association. What is the most likely missing configuration?

An engineer is troubleshooting a site-to-site VPN between a Cisco ASA and a Cisco IOS router. The VPN is configured using IKEv1 with pre-shared keys. The tunnel establishes and traffic flows, but after a few hours, the tunnel drops and re-establishes. The engineer checks the logs and sees that the Phase 1 SA is being rekeyed. What is the most likely reason for the tunnel dropping?

A network engineer is configuring a remote access VPN using Cisco AnyConnect on an ASA. The engineer wants to use certificate-based authentication. The ASA is configured with a CA server. After configuration, users can connect, but they are prompted for a username and password instead of using certificates. The engineer checks the ASA configuration and sees that the tunnel group has authentication method set to AAA. What should the engineer do to fix this?

A network engineer is configuring port security on a Cisco switch. The requirement is to allow only the first MAC address that appears on the port to be learned and to automatically disable the port if a violation occurs. The engineer configures 'switchport port-security mac-address sticky' but does not specify a maximum number of secure MAC addresses. After connecting a single host, the port works. However, when the host is replaced with a different device, the port is error-disabled. What is the most likely reason?

An enterprise network uses 802.1X for wired access. The authentication server is a Cisco ISE. Recently, some Windows 10 clients fail to authenticate, while others succeed. The engineer checks the switch configuration and finds 'authentication port-control auto' and 'dot1x pae authenticator' are configured. The failing clients show 'EAP failure' in the logs. The engineer suspects a mismatch in EAP method. Which EAP method is most likely causing the issue if the ISE is configured to require EAP-TLS but the Windows clients are configured for PEAP-MSCHAPv2?

A network engineer is configuring CoPP on a Cisco router to protect the control plane from excessive traffic. The router experiences high CPU utilization due to SSH and SNMP traffic. The engineer creates a class-map to match SSH (TCP/22) and SNMP (UDP/161) and applies a policy-map that polices this traffic to 1 Mbps. After applying the policy, legitimate SSH sessions from the management station start dropping intermittently. What is the most likely cause?

A network engineer is implementing DHCP snooping on a Cisco switch to prevent rogue DHCP servers. The switch has multiple VLANs, and the DHCP server is connected to interface GigabitEthernet0/1 in VLAN 10. The engineer enables DHCP snooping globally and for VLAN 10, then configures 'ip dhcp snooping trust' on GigabitEthernet0/1. However, clients in VLAN 10 are not receiving IP addresses. The engineer checks the DHCP snooping binding table and sees no entries. What is the most likely cause?

A network engineer is configuring dynamic ARP inspection (DAI) on a Cisco switch to prevent ARP spoofing. The switch has DHCP snooping enabled and the DHCP server is trusted. The engineer enables DAI on VLAN 10 and configures 'ip arp inspection trust' on the port connected to the DHCP server. After enabling DAI, some legitimate ARP replies from hosts are being dropped. The engineer checks the DAI statistics and sees 'ARP ACL drops' incrementing. What is the most likely reason?

A network engineer is configuring IPv6 First Hop Security on a Cisco switch to mitigate rogue RA attacks. The engineer enables RA guard on the switch and applies a policy that allows only the default gateway to send RAs. After configuration, hosts are unable to obtain IPv6 addresses via SLAAC. The engineer checks the switch and sees that RA guard is dropping all RAs. What is the most likely cause?

A network engineer needs to automate the backup of running configurations from multiple Cisco IOS XE devices to a central TFTP server. Which tool is best suited for this task in a Python-based automation framework?

An organization uses Cisco DNA Center to automate network provisioning. A network engineer deploys a new access switch but finds that the switch does not receive the intended configuration template. The switch appears in DNA Center inventory with status 'Managed'. What is the most likely cause?

A network team uses Ansible to automate VLAN configuration on Cisco IOS devices. The playbook fails with the error 'Failed to connect to the host via ssh: Permission denied (publickey)'. The control node runs Ubuntu, and the network devices are configured with SSH key authentication. Which solution should the engineer implement?

A company uses Cisco Catalyst Center (formerly DNA Center) for intent-based networking. After upgrading the Catalyst Center appliance, the engineer notices that some devices are unreachable via the network, but the Catalyst Center GUI shows them as 'Managed'. What is the most likely cause?

A network engineer is creating a Python script using the Cisco IOS XE RESTCONF API to configure a loopback interface. The script sends a PUT request to the URI /restconf/data/Cisco-IOS-XE-native:native/interface/Loopback=100 with a JSON body that includes the IP address. The API returns a 201 Created status, but the loopback interface does not appear in the running configuration. What is the most likely issue?

A network engineer uses Netmiko to connect to multiple Cisco IOS XE devices and execute commands. The script runs correctly for most devices but fails for one device with the error: 'ValueError: SSH session not active'. The device is reachable and SSH credentials are correct. What is the most likely cause?

A network engineer is writing a Python script to automate the backup of running configurations from a list of 50 Cisco IOS-XE devices. The script uses the netmiko library and a for loop to connect to each device, execute 'show run', and write the output to a file. After running the script, the engineer notices that the script fails on the 15th device with a timeout error, and the remaining devices are not processed. The engineer wants to ensure that if one device fails, the script continues with the next device. What is the best way to modify the script?

An engineer is using the Cisco DNA Center REST API to retrieve a list of network devices and their health scores. The engineer writes a Python script using the requests library. The script successfully retrieves data for the first 100 devices, but when trying to get the next 100, the API returns an empty list. The engineer checks the API documentation and finds that the endpoint supports pagination with the 'offset' and 'limit' parameters. The current script does not handle pagination. What should the engineer do to retrieve all devices?

A network engineer is automating the configuration of VLANs on a Cisco Nexus 9000 switch using Python and the NX-API. The engineer sends a Python dictionary with the CLI commands to the API and receives a successful response. However, when checking the switch, the VLANs are not created. The engineer verifies that the credentials and IP address are correct, and the API is enabled. The engineer also notices that the API response contains a 'code' field of '200' and a 'result' field that shows the command output. What is the most likely cause of the issue?

A junior engineer is tasked with writing a Python script that uses the Cisco IOS-XE RESTCONF API to retrieve the hostname of a router. The engineer uses the requests library and sends a GET request to the URL 'https://router/restconf/data/Cisco-IOS-XE-native:native/hostname'. The request returns a 404 Not Found error. The engineer has verified that the RESTCONF service is enabled and the credentials are correct. What is the most likely reason for the 404 error?

A network engineer is using the Cisco Meraki Dashboard API to automate the creation of VLANs across multiple networks. The engineer writes a Python script that uses the 'createNetworkVlan' endpoint. The script runs successfully for the first few networks, but then starts returning HTTP 429 errors. The engineer checks the API documentation and finds that the Meraki API has rate limits. The script currently sends requests as fast as possible. What should the engineer implement to avoid hitting the rate limit?

An engineer is writing a Python script to parse the output of 'show ip interface brief' from multiple Cisco routers. The engineer uses the netmiko library to collect the output and then uses regular expressions to extract the interface name, IP address, and status. The script works correctly for most routers, but on one router, the output format is slightly different (e.g., extra spaces or different column headers). The engineer wants to make the parsing more robust. What is the best approach?

A network engineer is automating the deployment of VLAN configurations on a set of Cisco IOS-XE switches using Ansible. The playbook uses the ios_vlans module and runs successfully on the first switch, but fails on the second switch with an error indicating that the module is not found. Both switches are running the same IOS-XE version and have the same management access configured. What is the most likely cause of this issue?

An engineer is writing an Ansible playbook to configure OSPF on a fleet of Cisco Nexus 9000 switches. The playbook uses the nxos_ospf module. When executed, the playbook reports 'changed' for every switch, even on subsequent runs when no configuration changes are made. The engineer wants to achieve idempotent behavior. What is the most likely cause of the non-idempotent results?

A network team uses Ansible Tower to manage configuration backups of 500 Cisco IOS routers. They have a playbook that uses the ios_config module with the 'backup: yes' option. Recently, backups started failing for a subset of routers, with errors like 'backup destination path does not exist'. The playbook uses a variable 'backup_dir' set in the Tower job template. What is the most likely cause of these failures?

An engineer is automating the configuration of SNMPv3 on a large number of Cisco IOS-XE devices using Ansible. The playbook uses the ios_snmp_server module. The engineer wants to ensure that the SNMP configuration is applied only if the device is running a specific IOS version that supports SNMPv3. Which Ansible feature should the engineer use to conditionally execute the task?

A network engineer is using Ansible to push ACL changes to a group of Cisco IOS routers. The playbook uses the ios_acl_interfaces module to bind ACLs to interfaces. After running the playbook, the engineer notices that some routers have the ACL applied inbound instead of outbound as intended. The playbook specifies 'direction: outbound'. What is the most likely cause of this issue?

An organization uses Ansible to manage network device configurations. They have a playbook that uses the ios_command module to execute 'show ip route' on multiple routers and then uses the 'debug' module to print the output. Recently, the playbook started failing with 'Timeout (12s) waiting for privilege escalation prompt'. The routers are reachable and SSH credentials are correct. What is the most likely cause?

A network engineer is automating the configuration of a new VLAN on a Cisco Catalyst 9000 switch using RESTCONF. The engineer sends a PUT request to the URI 'https://switch/restconf/data/Cisco-NX-OS-device:Native/VlanList' with a JSON payload containing the VLAN details. The switch responds with a 405 Method Not Allowed error. What is the most likely cause of this error?

An engineer is using a Python script to retrieve interface statistics from a Cisco IOS-XE device via the REST API. The script sends a GET request to 'https://device/restconf/data/ietf-interfaces:interfaces/interface=GigabitEthernet1/statistics' and receives a 404 Not Found response. The interface exists and is operational. What is the most likely issue?

A network team is using Ansible with the iosxr_config module to push configuration changes to a Cisco IOS-XR router. The playbook uses the REST API via the 'ansible_connection: restconf' setting. The engineer notices that the changes are applied but the playbook reports 'changed: false' even when changes were made. What is the most likely reason for this behavior?

An engineer is developing a script to automate the backup of running configurations from multiple Cisco IOS-XE devices using RESTCONF. The script sends a GET request to 'https://device/restconf/data/Cisco-IOS-XE-native:native/configuration' and receives a 501 Not Implemented error. What is the most likely cause?

A network engineer is using the Cisco DNA Center REST API to retrieve the list of network devices. The engineer sends a GET request to '/dna/intent/api/v1/network-device' and receives a 400 Bad Request response. The API documentation indicates that the request requires a query parameter 'siteId'. What should the engineer do to resolve the issue?