350-401 Practice Exam 52 — 20 Questions

Question 1

Drag and drop each STP port state on the left to its matching function on the right.

Accepted Answer

Blocking: Discards frames and listens for BPDUs. Blocking discards frames and listens for BPDUs; Listening listens for BPDUs only; Learning learns MAC addresses but does not forward; Forwarding sends and receives frames; Disabled is administratively down.

Question 2

A company is virtualizing its network functions using NFV on a KVM-based hypervisor. The design must ensure that the virtual router (CSR1000v) can handle high-throughput traffic with minimal latency. Which architectural consideration is most critical for achieving this goal?

Accepted Answer

Pin the vCPU of the CSR1000v to dedicated physical cores and ensure the VM memory is allocated from the same NUMA node.. Pinning vCPUs to dedicated physical cores and allocating memory from the same NUMA node eliminates cross-NUMA memory access and CPU scheduling contention, which are critical for reducing latency and maximizing throughput in a data-plane-intensive VNF like the CSR1000v. This ensures that the VM's memory accesses are local to the NUMA node where its vCPUs run, avoiding the performance penalty of remote memory access over the QPI/UPI interconnect.

Answer

Use a Type 2 hypervisor to allow the VNF to share resources with other VMs more efficiently.

Answer

Enable overcommitment of CPU resources to maximize the number of VNFs per host.

Answer

Place the CSR1000v on a VMware ESXi host instead of KVM for better performance.

Question 3

Drag and drop the steps of EIGRP route summarization configuration into the correct order, from first to last.

Accepted Answer

Enable EIGRP with router eigrp AS. EIGRP route summarization first requires enabling EIGRP, configuring the network statement, then entering interface configuration mode, applying the summary-address command, and finally verifying the summary route in the routing table.

Question 4

interface GigabitEthernet0/1
 spanning-tree portfast
 spanning-tree bpduguard enable
 end

What is the effect of this configuration?

Accepted Answer

The port will immediately transition to forwarding state and will be error-disabled if a BPDU is received.. The `spanning-tree portfast` command causes the port to immediately transition to the forwarding state, bypassing the listening and learning states. The `spanning-tree bpduguard enable` command places the port in an error-disabled state if any BPDU is received, as BPDU reception on a PortFast-enabled port indicates an unauthorized switch connection, which could cause a bridging loop.

Answer

The port will go through normal STP states and will be error-disabled if a BPDU is received.

Answer

The port will immediately transition to forwarding and ignore any BPDUs received.

Answer

The port will remain in blocking state until a BPDU is received.

Question 5

An enterprise is migrating its data center to a leaf-spine architecture to support high east-west traffic between servers. The design must provide non-blocking forwarding and allow for easy scaling by adding more spines. Which characteristic is essential for the spine switches in this design?

Accepted Answer

Spine switches must support high port density and high forwarding capacity, and act as Layer 3 routers. In a leaf-spine architecture designed for non-blocking forwarding and high east-west traffic, spine switches must act as Layer 3 routers with high port density and forwarding capacity. This allows them to perform Equal-Cost Multi-Path (ECMP) routing, which distributes traffic across all available uplinks without blocking, ensuring that any leaf can reach any other leaf with predictable latency and full bandwidth utilization.

Answer

Spine switches must run Spanning Tree Protocol (STP) to prevent loops

Answer

Spine switches must be connected to each other to provide redundancy

Answer

Spine switches must perform NAT to translate between VLANs

Question 6

Examine the following configuration on a Cisco IOS-XE switch:

interface GigabitEthernet0/5
 switchport mode trunk
 switchport trunk native vlan 999
 switchport trunk allowed vlan 10,20,30
 switchport nonegotiate

What is the effect of the 'switchport nonegotiate' command?

Accepted Answer

The interface will not send or process DTP frames, and remains a trunk.. The 'switchport nonegotiate' command disables Dynamic Trunking Protocol (DTP) on the interface. When configured on a trunk port, the interface will neither send nor process any DTP frames, ensuring the port remains in trunk mode regardless of the neighbor's DTP configuration. This is commonly used when connecting to non-Cisco devices that do not support DTP, or to prevent unwanted trunk negotiation.

Answer

The interface will not send DTP frames, but will still respond to incoming DTP frames.

Answer

The interface will revert to an access port.

Answer

The interface will negotiate trunking using ISL instead of DTP.

Question 7

A network architect is designing QoS for a converged network carrying voice, video, and data. The design must use the DiffServ model and ensure that voice traffic is marked with the highest priority and that video traffic is marked with a lower priority but still above data. Which DSCP markings should be assigned to voice and video traffic, respectively, to comply with the standard Per-Hop Behavior (PHB) definitions?

Accepted Answer

Voice: DSCP 46 (EF); Video: DSCP 34 (AF41). The DiffServ model defines specific Per-Hop Behaviors (PHBs) for different traffic types. Voice traffic requires low latency, jitter, and loss, which is best served by the Expedited Forwarding (EF) PHB, assigned DSCP 46. Video traffic, while still delay-sensitive, can tolerate some loss and is typically marked with Assured Forwarding (AF41, DSCP 34), which provides a lower priority queue than EF but higher than best-effort data.

Answer

Voice: DSCP 56 (CS7); Video: DSCP 48 (CS6)

Answer

Voice: DSCP 40 (AF41); Video: DSCP 46 (EF)

Answer

Voice: DSCP 26 (AF31); Video: DSCP 18 (AF21)

Question 8

A network engineer runs the following command on Switch SW1:

SW1# show spanning-tree vlan 10

VLAN0010
  Spanning tree enabled protocol ieee
  Root ID    Priority    32778
             Address     0011.2233.4455
             Cost        19
             Port        1 (GigabitEthernet0/1)
             Hello Time  2 sec  Max Age 20 sec  Forward Delay 15 sec

Bridge ID  Priority    32778  (priority 32768 sys-id-ext 10)
             Address     0011.2233.4466
             Hello Time  2 sec  Max Age 20 sec  Forward Delay 15 sec
             Aging Time  300 sec

Interface           Role Sts Cost      Prio.Nbr Type
------------------- ---- --- --------- -------- --------------------------------
Gi0/1               Root FWD 19        128.1    P2p
Gi0/2               Altn BLK 19        128.2    P2p

Based on this output, what can be concluded?

Accepted Answer

The local switch is not the root bridge for VLAN 10. The output shows that the local switch (Bridge ID 0011.2233.4466) has a Root ID of 0011.2233.4455, which is different from its own Bridge ID. Additionally, the Root Cost is 19, and the Root Port is Gi0/1. This confirms that the local switch is not the root bridge for VLAN 10; it is a non-root switch with a root port in the forwarding state.

Answer

The local switch is the root bridge for VLAN 10

Answer

Interface Gi0/2 is in a forwarding state

Answer

The spanning-tree mode is Rapid PVST+

Question 9

A network architect is designing QoS for a Cisco SD-WAN deployment that uses a mix of MPLS and broadband Internet transports. The design must ensure that interactive video traffic is not delayed by large file transfers, even when the Internet link experiences congestion. Which SD-WAN policy type should the architect use to enforce this behavior?

Accepted Answer

Configure a localized QoS policy on the WAN edge routers that matches video traffic and applies a priority queue.. A localized QoS policy on the WAN edge router can classify interactive video traffic and place it into a priority queue, ensuring low-latency treatment even when the Internet link is congested. This policy operates locally on the router, directly controlling queuing and scheduling behavior on the specific interface, which is essential for protecting real-time traffic from bulk file transfers.

Answer

Use a centralized data policy to steer video traffic to the MPLS link only.

Answer

Implement a centralized application-aware routing policy to prefer the MPLS link for video.

Answer

Configure a VPN membership policy to isolate video traffic in a separate VPN.

Question 10

Consider the following EIGRP configuration:

router eigrp 100
 metric weights 0 1 0 1 0 0

What does this configuration accomplish?

Accepted Answer

It sets the EIGRP metric to use bandwidth and delay only, which is the default behavior.. The `metric weights` command in EIGRP allows you to modify the K values used in the composite metric calculation. The default K values are K1=1, K2=0, K3=1, K4=0, K5=0, which means only bandwidth (K1) and delay (K3) are used. The configuration `metric weights 0 1 0 1 0 0` explicitly sets K1=1, K2=0, K3=1, K4=0, K5=0, which matches the default behavior. Therefore, option A is correct.

Answer

It disables the use of bandwidth in the metric calculation.

Answer

It enables the use of load and reliability in the metric calculation.

Answer

It changes the metric to use only delay.

Question 11

Drag and drop the steps of Syslog severity filtering and rate-limiting configuration into the correct order, from first to last.

Accepted Answer

Enable logging on device. First enable logging, then set severity, apply rate-limit, specify destination, and finally verify the configuration.

Question 12

Examine the following configuration snippet:
interface GigabitEthernet0/1
 ip address 192.168.1.1 255.255.255.0
 ip ospf network point-to-point
 ip ospf hello-interval 10
 ip ospf dead-interval 40
!
router ospf 1
 network 192.168.1.0 0.0.0.255 area 0

What is the effect of this configuration?

Accepted Answer

OSPF adjacency will form with a neighbor using hello/dead intervals of 10/40 seconds.. The configuration sets the OSPF network type to point-to-point on the interface, which allows OSPF to form an adjacency with a neighbor using the configured hello interval of 10 seconds and dead interval of 40 seconds. These intervals are valid for point-to-point networks, and the network command under router ospf correctly enables OSPF on the interface. Therefore, an adjacency will form as long as the neighbor's intervals match.

Answer

OSPF adjacency will not form because the hello interval is too low for point-to-point.

Answer

The network command under router ospf will be ignored because the interface has an explicit network type.

Answer

OSPF will use the default broadcast network type because the point-to-point keyword is misspelled.

Question 13

Which three statements about Multiple Spanning Tree Protocol (MSTP) are true? (Choose three.)

Accepted Answer

MSTP allows multiple VLANs to be grouped into a single spanning-tree instance, reducing CPU and memory usage.. MSTP (IEEE 802.1s) allows multiple VLANs to be mapped to a single spanning-tree instance (MST instance), reducing the number of STP instances needed. It uses an Internal Spanning Tree (IST) instance (instance 0) that always runs and carries BPDUs for the region. Switches in the same MST region must have identical VLAN-to-instance mappings, revision number, and region name. MSTP interoperates with Rapid PVST+ at region boundaries by using PVST simulation mode. MSTP does not require a separate root bridge for each VLAN; instead, each MST instance has its own root bridge.

Answer

MSTP automatically load-balances traffic across all available uplinks without any configuration.

Answer

MSTP requires a separate root bridge to be elected for each VLAN in the network.

Question 14

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?

Accepted Answer

The router's system clock is not synchronized via NTP or manual setting.. The 'service timestamps log datetime msec' command tells the router to include a timestamp in syslog messages, but the timestamp is derived from the router's system clock. If the clock is not synchronized via NTP or manually set, the local logs will show incorrect timestamps. The syslog server, however, receives the messages and applies its own timestamp upon receipt, which is why the server shows the correct time. Therefore, the mismatch is caused by the router's unsynchronized clock.

Answer

The 'service timestamps log datetime msec' command is not supported on this platform.

Answer

The syslog server is overwriting the timestamps.

Answer

The 'logging host' command must include the 'transport tcp' option.

Question 15

A network engineer configures SNMPv2c on a Cisco switch to send traps to an NMS. The engineer uses 'snmp-server community public RO' and 'snmp-server host 10.1.1.1 version 2c public'. The NMS receives traps, but the engineer notices that the traps contain the IP address of the management interface (VLAN 1) instead of the loopback interface (Loopback0) that is used for management. The engineer wants the traps to use the loopback IP as the source. What should the engineer do?

Accepted Answer

Configure 'snmp-server trap-source Loopback0'.. The correct command to set the source IP address for SNMP traps on a Cisco device is 'snmp-server trap-source Loopback0'. This command forces all SNMP trap messages to use the IP address of the specified interface as the source, regardless of which interface they exit. Option B is correct because it directly configures the trap source to the loopback interface, ensuring the NMS sees the loopback IP instead of the VLAN 1 management IP.

Answer

Configure 'snmp-server source-interface traps Loopback0'.

Answer

Configure 'ip snmp source-interface Loopback0'.

Answer

Change the management interface IP to match the loopback.

Question 16

What is the maximum hop count for EIGRP?

Accepted Answer

100. EIGRP uses a metric based on bandwidth and delay, but it also has a hop count limit. The default maximum hop count is 100, but it can be configured up to 255.

Answer

15

Answer

255

Answer

Unlimited

Question 17

Drag and drop each SNMP operation on the left to its matching direction on the right.

Accepted Answer

GET: Manager to agent. GET, GETNEXT, GETBULK, and SET are manager-to-agent requests; TRAP and INFORM are agent-to-manager notifications.

Question 18

Drag and drop the steps of OSPF virtual link configuration across area 0 into the correct order, from first to last.

Accepted Answer

Identify ABRs and transit area (not area 0). Virtual links require area 0 transit area, and must be configured on both ABRs. The steps ensure proper connectivity: identify endpoints, configure on each router, and verify.

Question 19

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?

Accepted Answer

The remote router must have an IP SLA responder configured to process the UDP jitter probes.. For UDP jitter IP SLA operations to collect jitter and latency statistics, the remote router must be configured as an IP SLA responder. The responder processes the probe packets and sends back time-stamped responses, which are essential for calculating jitter and one-way delay. Without the responder, the source router can send probes (showing 'Active' state) but cannot compute meaningful statistics because it never receives the required response packets.

Answer

The IP SLA operation must be configured with a 'request-data-size' value to match the remote router's MTU.

Answer

The source router needs a 'frequency' setting that matches the remote router's response interval.

Answer

The firewall on the remote router is blocking the UDP port 16384, preventing the probe from reaching the target.

Question 20

A network engineer is troubleshooting a BGP issue where a router is not installing a specific prefix in its routing table, even though the prefix is present in the BGP table. The engineer runs 'show ip bgp 10.0.0.0/24' and sees that the route is valid but not best. The BGP table shows that the route has a higher local preference than the current best path, but the AS_PATH is longer. What is the most likely reason the route is not being selected as best?

Accepted Answer

The route with higher local preference has a lower weight than the current best path.. BGP selects the best path based on a sequence of comparison steps. Local preference is checked before AS_PATH length, so a higher local preference should normally win. However, weight is the very first criterion in the BGP best-path selection algorithm. If the current best path has a higher weight than the route with higher local preference, weight overrides local preference, making the higher-local-preference route not best.

Answer

The route with higher local preference has a higher MED value.

Answer

The route with higher local preference is not synchronized with IGP.

Answer

The route with higher local preference was learned from an eBGP peer, while the current best path is from an iBGP peer.