350-601 Network Practice Test 12 — 15 Questions

Question 1

A network engineer is troubleshooting an OSPF adjacency that fails to reach FULL state between two Nexus 9000 switches. Which TWO are common causes for this issue?

Accepted Answer

Mismatched area ID. OSPF requires that both routers in a neighbor relationship belong to the same area. If the area IDs differ, the routers will not exchange routing information and the adjacency will stall at the EXSTART or EXCHANGE state, never reaching FULL. This is a fundamental OSPF neighbor requirement defined in RFC 2328.

Answer

Mismatched OSPF process ID

Answer

Mismatched router ID

Answer

Mismatched network type

Question 2

A data center runs OSPF as the underlay for an EVPN-VXLAN fabric. The fabric includes two spine switches and eight leaf switches. After adding a new leaf switch, the network team notices that some EVPN routes are missing from the other leaves. The new leaf has established BGP EVPN sessions to both spines and the BGP sessions are up. The spines report receiving all routes from the new leaf, but the other leaves do not receive certain prefixes. The engineer checks the BGP configuration on the new leaf and sees the address-family l2vpn evpn is configured under router bgp. Which action should the engineer take to resolve the issue?

Accepted Answer

Verify the new leaf has the address-family l2vpn evpn activated under the neighbor configuration. The issue is that the new leaf has BGP EVPN sessions to both spines, but other leaves do not receive certain prefixes. Since the spines (acting as route reflectors) receive all routes from the new leaf but do not propagate them to other leaves, the most likely cause is that the address-family l2vpn evpn is not activated under the neighbor configuration on the new leaf. Without this activation, the new leaf does not advertise its EVPN routes to the spines, even though the BGP session is up and the address-family is configured globally under router bgp.

Answer

Check the new leaf's BGP router ID for uniqueness

Answer

Ensure the new leaf's BGP next-hop-self is enabled

Answer

Verify the cluster ID on the route reflectors is consistent

Question 3

In a VXLAN overlay network, which component is responsible for encapsulating and decapsulating packets and resides at the edge of the underlay network?

Accepted Answer

VTEP. C is correct because the VXLAN Tunnel Endpoint (VTEP) is the device at the edge of the underlay network that performs encapsulation and decapsulation of VXLAN packets. It adds a VXLAN header (including a 24-bit VNI) and outer UDP/IP headers to original Layer 2 frames, and removes them on the receiving side. This function is defined in RFC 7348 and is essential for extending Layer 2 segments over a Layer 3 underlay.

Answer

VNI

Answer

NSX Controller

Answer

Leaf switch

Question 4

In Cisco ACI, which component is responsible for translating EPG communication policies into concrete configuration on leaf switches?

Accepted Answer

APIC controller. The APIC controller is the centralized policy engine in Cisco ACI. It translates high-level EPG communication policies (contracts, filters, subjects) into the concrete switch configuration (e.g., OpFlex policy elements, VXLAN tunnel mappings, and hardware table entries) and pushes them to leaf switches via the OpFlex protocol. Without the APIC, leaf switches cannot autonomously interpret or apply these policies.

Answer

Leaf switch

Answer

Spine switch

Answer

VMM domain

Question 5

Which NX-OS command displays the vPC consistency parameters and status on a Cisco Nexus switch?

Accepted Answer

show vpc consistency-parameters. The 'show vpc consistency-parameters' command is the correct choice because it directly displays the vPC consistency parameters and their status, which are critical for ensuring that both vPC peer switches have identical configurations for type-1 parameters (e.g., STP, VLANs, MTU). If these parameters mismatch, the vPC will be suspended to prevent traffic loops or forwarding issues. This command is the dedicated tool for verifying consistency before and after vPC configuration changes.

Answer

show vpc peerlink

Answer

show vpc brief

Answer

show running-config vpc

Question 6

In a VXLAN EVPN fabric, BUM traffic can be handled by ingress replication or multicast. Which statement about ingress replication is accurate?

Accepted Answer

The ingress VTEP replicates the BUM packet and sends unicast copies to each remote VTEP.. In ingress replication, the ingress VTEP (VXLAN Tunnel Endpoint) receives a BUM (Broadcast, Unknown unicast, Multicast) packet and creates multiple unicast-encapsulated copies, sending one copy to each remote VTEP in the same VXLAN network identifier (VNI) segment. This method does not rely on any multicast protocol in the underlay; instead, it leverages the VTEP's knowledge of all remote VTEPs (typically learned via the EVPN control plane, such as Type 3 Inclusive Multicast Ethernet Tag routes) to replicate traffic. Option B correctly describes this behavior.

Answer

It requires PIM in the underlay to replicate packets.

Answer

It reduces replication overhead on the ingress VTEP compared to multicast.

Answer

It uses IGMP snooping to optimize replication.

Question 7

In a spine-leaf architecture with 40 leaf switches and 4 spine switches, each leaf has four 40G uplinks to the spines. What is the oversubscription ratio if each leaf has 48 ports of 10G for servers?

Accepted Answer

3:1. The oversubscription ratio is calculated by comparing total server bandwidth to total uplink bandwidth. Each leaf has 48 ports × 10G = 480G of server-facing bandwidth, and 4 uplinks × 40G = 160G of spine-facing bandwidth. The ratio is 480:160 = 3:1, meaning three times as much server bandwidth as uplink bandwidth, which is a common design target in Cisco ACI and NX-OS spine-leaf fabrics.

Answer

2:1

Answer

5:1

Answer

4:1

Question 8

An engineer needs to extend a Layer 2 VLAN across a VXLAN EVPN fabric. Which construct maps the VLAN to the overlay network?

Accepted Answer

VNI. In a VXLAN EVPN fabric, the VNI (VXLAN Network Identifier) is the construct that maps a Layer 2 VLAN to the overlay network. The VNI uniquely identifies a Layer 2 segment across the underlay, allowing VLAN traffic to be encapsulated and transported over the IP fabric. This mapping is configured on the VTEP (VXLAN Tunnel Endpoint) using commands like 'vlan 100' mapped to 'vn-segment 10100' under the VLAN configuration.

Answer

VLAN ID

Answer

VTEP IP

Answer

VPC

Question 9

In a Cisco ACI fabric, which component is responsible for policy enforcement and management of the entire infrastructure?

Accepted Answer

APIC controller. The APIC (Application Policy Infrastructure Controller) is the central policy and management entity in Cisco ACI. It enforces the application-centric policy model, manages the fabric's operational state, and provides the single point of configuration and monitoring for the entire ACI fabric. Without the APIC, the leaf and spine switches operate as standalone devices with no centralized policy enforcement.

Answer

Leaf switch

Answer

DCNM

Answer

Spine switch

Question 10

A data center engineer is configuring vPC on a pair of Cisco Nexus switches. The vPC peer-link is established but the vPC member ports remain suspended. After checking the configuration, the engineer notices that the vPC peer-keepalive link is not functioning. What is the most likely cause of the suspended member ports?

Accepted Answer

Peer-keepalive link failure causing dual-active detection issues. When the vPC peer-keepalive link fails, each vPC peer switch cannot detect whether the other peer is operational. This triggers the dual-active detection mechanism, causing the secondary switch to suspend its vPC member ports to prevent a split-brain scenario where both switches forward traffic for the same vPC VLAN. The suspended state is a protective measure until the peer-keepalive link is restored or the vPC role is resolved.

Answer

MTU mismatch on the peer-link

Answer

Mismatched vPC domain ID

Answer

Incorrect VLAN configuration on member ports

Question 11

In a spine-leaf architecture using eBGP as the routing protocol, what is the primary purpose of using eBGP rather than iBGP between spine and leaf switches?

Accepted Answer

To avoid the need for an IGP and simplify configuration. In a spine-leaf architecture using eBGP, the primary purpose is to avoid the need for an IGP (such as OSPF or IS-IS) and simplify configuration. eBGP between spine and leaf switches allows each leaf to be in a different private AS (e.g., 65001–650XX), and the spine can use the BGP AS_PATH to detect and prevent loops without requiring an underlying IGP. This eliminates the complexity of running a separate IGP for underlay routing, reducing operational overhead and configuration steps.

Answer

To enable faster convergence than OSPF

Answer

To support EVPN address families

Answer

To allow for unequal-cost load balancing

Question 12

An engineer is configuring MST on a pair of Cisco Nexus switches that will be part of a vPC domain. The vPC peer-link will carry multiple MST instances. Which MST parameter must be identical on both vPC peers to ensure proper operation?

Accepted Answer

MST region configuration (name, revision, mapping). In a vPC domain with MST, both peers must share an identical MST region configuration (name, revision number, and VLAN-to-instance mapping) to ensure they agree on which VLANs belong to which MST instance. Without matching region configurations, the switches would treat each other as being in different MST regions, breaking the common spanning tree topology required for the vPC peer-link to properly carry multiple MST instances.

Answer

PortFast and BPDUguard settings

Answer

STP root bridge priority

Answer

STP path cost for instance 0

Question 13

Which VXLAN component is responsible for encapsulating and decapsulating Ethernet frames into UDP packets?

Accepted Answer

VTEP. The VTEP (VXLAN Tunnel Endpoint) is the device that performs encapsulation and decapsulation of Ethernet frames into UDP packets. It is the edge component in a VXLAN network that maps tenant traffic to VXLAN segments and handles the actual tunneling by adding the VXLAN header (including VNI) and outer UDP/IP headers.

Answer

VNI

Answer

VXLAN tunnel

Answer

VXLAN gateway

Question 14

Which Cisco NX-OS feature allows automation and programmatic access to device configuration and monitoring using REST APIs?

Accepted Answer

NX-API. NX-API is the correct answer because it provides a REST-based API interface on Cisco NX-OS devices, allowing automation and programmatic access to configuration and monitoring via HTTP/HTTPS methods (GET, POST, PUT, DELETE). It exposes the device's CLI commands as RESTful API calls, enabling tools like Ansible, Postman, or custom scripts to interact with the switch without requiring SSH or direct CLI access.

Answer

Python scripting

Answer

Bash shell access

Answer

SNMP

Question 15

In a VXLAN EVPN fabric, a new server is connected to a leaf switch and requires Layer 2 connectivity to an existing VM on a different leaf. The engineer notes that the VTEP on the new leaf does not have a Type-2 route for the VM's MAC address. Which EVPN route type is used to advertise MAC addresses?

Accepted Answer

Type-2 (MAC/IP Advertisement). In VXLAN EVPN fabrics, Type-2 (MAC/IP Advertisement) routes are specifically used to advertise MAC addresses and their associated IP addresses between VTEPs. When a new leaf switch needs Layer 2 connectivity to a VM on a different leaf, it must learn the VM's MAC address via a Type-2 route from the remote VTEP. Without this route, the new leaf cannot populate its MAC table for that VM, preventing Layer 2 communication.

Answer

Type-5 (IP Prefix)

Answer

Type-1 (Ethernet Auto-discovery)

Answer

Type-3 (Inclusive Multicast Ethernet Tag)