CCNP Infrastructure Practice Test 13 — 15 Questions

Question 1

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?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

The interface MTU does not match.. When OSPF neighbors are stuck in the EXSTART state, it typically indicates a problem with the Database Description (DBD) packet exchange process. The most common cause is an MTU mismatch between the interfaces, because OSPF will not proceed to the Exchange state if the DBD packet is larger than the interface MTU and gets silently dropped. This prevents the routers from agreeing on the master/slave relationship and exchanging link-state information.

Answer

The router ID is the same on both routers.

Answer

The area ID is different.

Answer

The hello timer is set to 30 seconds on one router.

Question 2

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

Accepted Answer

vlan 100. The correct command to create a new VLAN on a Cisco IOS switch is 'vlan 100' entered in global configuration mode. This command creates VLAN 100 and enters VLAN configuration mode, allowing you to assign a name or other parameters. The other options either apply an existing VLAN to an interface, use a deprecated method, or create a switched virtual interface (SVI) for Layer 3 routing, none of which actually create the VLAN itself.

Answer

switchport access vlan 100

Answer

vlan database

Answer

interface vlan 100

Question 3

A company has a requirement to provide redundancy for the default gateway on a subnet. Two switches are configured with HSRP. Which requirement must be met for the interfaces on the switches to form the HSRP group?

Accepted Answer

The interfaces must be in the same VLAN.. HSRP is a First Hop Redundancy Protocol that provides a virtual gateway for hosts. To form an HSRP group, the participating interfaces must be Layer 3 interfaces (either SVIs on switches or routed ports on multilayer switches) that are configured with IP addresses and belong to the same VLAN. Option B is incorrect because HSRP does not run on Layer 2 switchports; those ports do not have IP addresses and cannot send HSRP messages. Option D is correct because being in the same VLAN ensures the switches share the same broadcast domain, allowing HSRP multicast hello messages to reach each other.

Answer

The interfaces must be on the same physical switch.

Answer

The interfaces must be Layer 2 switchports.

Answer

The interfaces must have the same IP address.

Question 4

A company has a campus network with two distribution switches (DSW1 and DSW2) connected via a Layer 2 trunk. Each distribution switch connects to two access switches. Spanning Tree Protocol (STP) is running with default settings. Recently, a network administrator added a new access switch (ASW3) and connected it to both distribution switches. After the connection, network performance degraded significantly, and users in VLAN 10 reported intermittent connectivity. The administrator checked the logs and saw multiple TCN notifications. What is the most likely cause of the issue?

Accepted Answer

The new switch is causing a Layer 2 loop due to redundant links without proper STP configuration.. When ASW3 is connected to both DSW1 and DSW2 via Layer 2 trunk links, it creates a physical loop in the network. With default STP settings, the new switch will participate in the spanning tree algorithm, but the sudden addition of redundant links can cause a temporary loop or instability until STP converges. The multiple TCN (Topology Change Notification) messages indicate that the spanning tree topology is flapping, leading to MAC address table flushes and intermittent connectivity for VLAN 10 users. This is the classic symptom of a Layer 2 loop caused by redundant links without proper STP configuration or before convergence completes.

Answer

The new switch is not configured with the same VLANs as the distribution switches.

Answer

The new switch has a lower bridge priority than the current root bridge.

Answer

The new switch has become the root bridge and is sending inferior BPDUs.

Question 5

A multinational organization has a BGP-based MPLS VPN network. The CE router at a branch office is connected to two PE routers (PE1 and PE2) in the service provider network. The branch uses eBGP to exchange routes with the PEs. The network administrator notices that the branch can reach some destinations but not others. The BGP table on the CE shows routes with next-hop set to the PE loopback addresses, but those loopbacks are not reachable. The CE has a default route pointing to the PEs. What is the most likely cause of the issue?

Accepted Answer

The next-hop addresses of the BGP routes are not reachable.. The CE router learns BGP routes from the PE routers with next-hop addresses set to the PE loopback interfaces. For these routes to be installed in the routing table, the CE must have a route to the next-hop IP address. Since the CE only has a default route pointing to the PEs and the PE loopbacks are not directly connected or reachable via any specific route, the BGP routes remain hidden (not installed) because the next-hop is unreachable. This is the most likely cause of partial reachability.

Answer

The default route on the CE is overriding the BGP routes.

Answer

The routes have an AS path that is too long.

Answer

The CE is not advertising its routes to the PEs.

Question 6

Refer to the exhibit. R1 has two equal-cost OSPF E2 routes to 10.1.1.0/24 via two different next hops. However, when tracing to 10.1.1.1, all traffic uses the path through 10.0.1.2. What is the most likely reason?

Accepted Answer

OSPF E2 routes do not factor interface cost; but the router uses the interface cost as a tie-breaker for equal-cost routes.. OSPF E2 routes do not include the internal cost to the ASBR; the cost shown in the routing table is the external metric only. When two E2 routes have the same external metric, Cisco IOS uses the interface cost as a tie-breaker to select the best next hop. In this scenario, the interface to 10.0.1.2 has a lower cost than the interface to 10.0.2.2, so all traffic is forwarded via 10.0.1.2.

Answer

One route has a higher administrative distance.

Answer

A default route is overriding the specific route.

Answer

The route via 10.0.2.2 is an E1 route.

Question 7

A network engineer is configuring a new Cisco IOS switch that will be deployed in a data center. The switch must forward traffic for VLAN 10 while ensuring that the native VLAN for all trunk ports is not susceptible to VLAN hopping attacks. The engineer decides to change the native VLAN from the default to an unused VLAN 999. Which command sequence correctly configures the native VLAN on a trunk port?

Accepted Answer

interface GigabitEthernet0/1
 switchport mode trunk
 switchport trunk native vlan 999. The correct configuration requires entering interface configuration mode, setting the port to trunk mode, and then specifying the native VLAN with 'switchport trunk native vlan 999'. This ensures that untagged traffic is associated with an unused VLAN, reducing VLAN hopping risk. The other options either misconfigure the port mode or do not properly set the native VLAN.

Answer

vlan 999
 name NATIVE
interface GigabitEthernet0/1
 switchport mode trunk
 switchport trunk allowed vlan 999

Answer

interface GigabitEthernet0/1
 switchport trunk encapsulation dot1q
 switchport trunk native vlan 999
 switchport mode trunk

Answer

interface GigabitEthernet0/1
 switchport mode access
 switchport access vlan 999

Question 8

A network engineer is deploying a VXLAN EVPN fabric. The underlay is a routed Layer 3 network using OSPF. Hosts in the same subnet are attached to leaf switches that are not directly connected. The engineer must ensure that the fabric provides optimal forwarding for East-West traffic without tromboning through a centralized gateway. Which VXLAN component should be configured to accomplish this?

Accepted Answer

Anycast distributed gateway with the same MAC and IP on all leaf switches. An anycast distributed gateway places the same gateway IP and MAC on every leaf switch, allowing each leaf to route traffic for its local hosts. This eliminates the need to send traffic to a centralized gateway, providing optimal East-West forwarding. It is a key feature of VXLAN EVPN fabrics for efficient inter-subnet routing.

Answer

OSPF area 0 with stub areas on all leaf switches to reduce LSAs

Answer

Static VXLAN tunnel endpoints mapped to each leaf switch's loopback address

Answer

VXLAN Network Identifier (VNI) mapping to a single centralized gateway

Question 9

A network engineer configured a router with the command `ip route 0.0.0.0 0.0.0.0 192.168.1.1` and also has a specific static route for 10.1.1.0/24 pointing to 192.168.1.1. A packet arrives destined for 10.1.1.5. Which route will the router use to forward the packet?

Accepted Answer

The specific static route for 10.1.1.0/24 because it has a longer prefix length.. The correct answer is the specific static route for 10.1.1.0/24. Cisco IOS uses longest prefix match to select the best route. A default route (0.0.0.0/0) is the least specific and is only used when no other route matches. Since a more specific route exists for the destination, that route is chosen.

Answer

The default route because it is less specific and matches all destinations.

Answer

The router will load-balance the packet across both routes.

Answer

The packet will be dropped because of conflicting static routes.

Question 10

A network engineer is deploying a new branch office switch and needs to configure a switched virtual interface (SVI) to act as the default gateway for VLAN 10. The VLAN has been created and ports have been assigned. Which additional step is required for the SVI to become operational and pass traffic?

Accepted Answer

Assign an IP address to the SVI with the interface vlan 10 command, then issue no shutdown.. An SVI requires an IP address and must be enabled with no shutdown. The VLAN must exist and have at least one active access port for the SVI to come up. Global IP routing is needed for inter-VLAN routing but does not affect the SVI's operational state. Trunking or port-channels are unrelated to bringing up an SVI for a single VLAN.

Answer

Configure a physical port as a trunk and allow VLAN 10 on it.

Answer

Enable IP routing globally with the ip routing command.

Answer

Assign the SVI to a port-channel for redundancy.

Question 11

A network engineer is deploying a new branch office that uses a single switch stack with two member switches. The stack must forward traffic between access ports in different VLANs without involving an external router. Which feature should be configured to meet this requirement?

Accepted Answer

Configure an SVI for each VLAN on the switch stack and enable IP routing with the ip routing command.. The requirement is to route traffic between VLANs using the switch stack itself. Creating switched virtual interfaces for each VLAN and enabling IP routing allows the stack to perform inter-VLAN routing without an external router. This is a standard design for collapsed core or branch offices where a multilayer switch provides both Layer 2 and Layer 3 forwarding.

Answer

Configure private VLANs on the access ports to allow communication between VLANs.

Answer

Configure VTP transparent mode on all switches and create the VLANs manually.

Answer

Configure 802.1Q trunk links between the two stack members and enable dynamic ARP inspection.

Question 12

A network administrator is configuring a Cisco IOS router to authenticate management users against a TACACS+ server. The administrator wants to ensure that if the TACACS+ server becomes unreachable, a local username and password can still be used to log in. Which configuration accomplishes this requirement?

Accepted Answer

aaa authentication login default group tacacs+ local. The correct method list must list 'group tacacs+' before 'local' so that TACACS+ is tried first, and local is used only if the server is unreachable. The 'local' keyword ensures that the local username database is used as a fallback. Other keywords like 'enable' or 'none' do not provide the required local username and password fallback.

Answer

aaa authentication login default local group tacacs+

Answer

aaa authentication login default group tacacs+ none

Answer

aaa authentication login default group tacacs+ enable

Question 13

A network administrator is configuring a new Cisco IOS router and needs to enable OSPFv3 for IPv6 on an interface. The interface is already configured with an IPv6 address. Which command must be entered in interface configuration mode to enable OSPFv3 on that interface?

Accepted Answer

ipv6 ospf 1 area 0. To enable OSPFv3 for IPv6 on an interface in Cisco IOS, the correct interface configuration command is 'ipv6 ospf area '. This command activates OSPFv3 on the interface and links it to the specified OSPFv3 process and area. The process ID must match the one defined in the global 'ipv6 router ospf' command. Without this command, the interface will not participate in OSPFv3 routing.

Answer

ospfv3 1 ipv6 area 0

Answer

ipv6 router ospf 1

Answer

ip ospf 1 area 0

Question 14

A network engineer is configuring a Cisco IOS router to authenticate OSPF neighbors using MD5. The engineer enters the following commands under the OSPF process: area 0 authentication message-digest, and under the interface: ip ospf message-digest-key 1 md5 Cisco123. However, the neighbor relationship does not form. What is the most likely cause?

Accepted Answer

The key ID and key string must match on both routers, and the area authentication command must be consistent.. OSPF MD5 authentication requires consistent configuration on both neighbors: the same key ID, the same key string, and the same authentication mode (area or interface). The area authentication command enables MD5 for the area, and the interface command provides the key. If any of these differ, OSPF authentication fails, and the routers will not become adjacent.

Answer

The area authentication command must be configured on all routers in the area, but the interface command is optional.

Answer

The key ID must match on both routers, but the key string can be different.

Answer

The router must be reloaded for the MD5 key to take effect.

Question 15

A network administrator is deploying a new branch office that requires a dynamic routing protocol supporting unequal-cost load balancing and fast convergence. The topology includes Cisco routers only. Which routing protocol should be implemented?

Accepted Answer

EIGRP. EIGRP is the only protocol among the choices that inherently supports unequal-cost load balancing via the variance feature and provides fast convergence through its feasible successor mechanism. OSPF and BGP support only equal-cost multipath, and RIPv2 lacks both features, making EIGRP the correct choice for this scenario.

Answer

BGP

Answer

OSPF

Answer

RIPv2