350-601 Network Practice Test 15 — 15 Questions

Question 1

In a spine-leaf data center architecture, what is the primary purpose of using equal-cost multipath (ECMP) routing?

Accepted Answer

To provide load balancing across multiple paths between leaf and spine switches. In a spine-leaf architecture, ECMP is used to distribute traffic across multiple equal-cost paths between leaf and spine switches. This provides load balancing by hashing flows across available uplinks, maximizing bandwidth utilization and ensuring no single link is overwhelmed. ECMP is a Layer 3 routing feature that operates with protocols like OSPF or BGP, not a Layer 2 or encapsulation mechanism.

Answer

To enable VXLAN encapsulation between VTEPs

Answer

To ensure loop-free Layer 2 topology

Answer

To reduce the number of VLANs required in the fabric

Question 2

An engineer is configuring vPC on a pair of Nexus switches. Which statement correctly describes the vPC peer-keepalive link?

Accepted Answer

It is a Layer 3 link used to verify the health of the vPC peer. The vPC peer-keepalive link is a Layer 3 link used exclusively to monitor the health of the vPC peer. It sends periodic keepalive messages (typically using UDP port 3200) to detect if the peer switch has failed, enabling the surviving switch to take over the vPC traffic. This link does not carry data traffic, BPDUs, or control-plane information beyond the keepalive probes.

Answer

It is used to forward data traffic between vPC peers

Answer

It must be a dedicated Layer 2 link between vPC peers

Answer

It carries BPDUs to prevent loops

Question 3

An engineer is designing an ACI fabric and needs to provide connectivity to an external Layer 3 network. Which construct must be configured to achieve this?

Accepted Answer

L3Out. To connect an ACI fabric to an external Layer 3 network, you must configure an L3Out. An L3Out defines the external routed connectivity by associating a VRF with external interfaces, routing protocols (e.g., OSPF, BGP, EIGRP), and subnets that are advertised into or from the fabric. This construct allows ACI to exchange routes with the external Layer 3 domain.

Answer

VMM domain

Answer

EPG

Answer

VXLAN tunnel

Question 4

Which BGP variant is commonly used in spine-leaf fabrics to advertise EVPN routes for VXLAN?

Accepted Answer

MP-BGP with EVPN address family. MP-BGP with the EVPN address family (AFI 25 / SAFI 70) is the control-plane protocol used in VXLAN spine-leaf fabrics to advertise MAC/VTEP reachability, host routes, and integrated routing and bridging (IRB) information. This allows the spine to act as a route reflector, distributing EVPN type-2 (MAC/IP) and type-3 (IMET) routes to all leaf nodes, enabling efficient, loop-free overlay forwarding.

Answer

OSPF with opaque LSA

Answer

eBGP with standard IPv4 unicast

Answer

iBGP with standard IPv4 unicast

Question 5

In a data center running MST, which region configuration parameter must match on all switches for them to be part of the same region?

Accepted Answer

Region name, revision number, and VLAN-to-instance mapping. In Multiple Spanning Tree (MST), switches must agree on three parameters to belong to the same MST region: the region name, the revision number, and the VLAN-to-instance mapping. These parameters are exchanged in MST BPDUs, and if any differ, the switches treat each other as being in different regions, which can lead to suboptimal or incorrect spanning-tree behavior.

Answer

Spanning-tree mode

Answer

Bridge priority

Answer

Max-age and hello time

Question 6

In a VXLAN overlay, what is the role of the VXLAN Network Identifier (VNI)?

Accepted Answer

It identifies the overlay Layer 2 network segment. The VXLAN Network Identifier (VNI) is a 24-bit field in the VXLAN header that uniquely identifies an overlay Layer 2 network segment, allowing multiple isolated Layer 2 domains to coexist over a shared Layer 3 underlay. It is analogous to a VLAN ID in traditional networking but provides up to 16 million segments, enabling scalable network virtualization.

Answer

It identifies the VXLAN tunnel source and destination IP

Answer

It is the multicast group address for BUM traffic

Answer

It is used for ECMP load balancing

Question 7

Which NX-OS command is used to display the current OSPF neighbor states?

Accepted Answer

show ip ospf neighbors. The 'show ip ospf neighbors' command is the correct NX-OS command to display the current OSPF neighbor states, including the neighbor ID, interface, state (e.g., FULL, 2WAY, DOWN), and adjacency details. This command directly queries the OSPF process for the neighbor state machine, which is essential for verifying OSPF adjacency formation and troubleshooting Layer 3 connectivity.

Answer

show ip route ospf

Answer

show ospf database

Answer

show ip ospf interface

Question 8

A data center designer is evaluating oversubscription ratios in a spine-leaf topology with 40 leaf switches and 4 spine switches. Each leaf has 4x100G uplinks to spines, and each spine has 40x100G downlinks. The leaf switches have 48x25G server ports. What is the oversubscription ratio from the server ports to the spine uplinks?

Accepted Answer

3:1. The oversubscription ratio is calculated by comparing total server bandwidth to total uplink bandwidth. Each leaf has 48x25G server ports = 1200G, and 4x100G uplinks = 400G, giving a leaf-level ratio of 3:1 (1200:400). Since all leaves are identical and the spine count doesn't affect the leaf-level ratio, the overall ratio remains 3:1.

Answer

2:1

Answer

4:1

Answer

5:1

Question 9

An engineer needs to automate a repetitive configuration task on a Nexus switch. Which method is most suitable for programmatic access?

Accepted Answer

NX-API. NX-API provides a RESTful interface that allows programmatic access to Nexus switches using HTTP/HTTPS methods (GET, POST, DELETE) with JSON or XML payloads. This makes it the most suitable method for automating repetitive configuration tasks because it supports modern scripting languages (Python, Ansible) and enables idempotent, structured configuration changes without requiring interactive CLI sessions.

Answer

FTP file transfer

Answer

CLI scripting with Tcl

Answer

SNMP v3

Question 10

An engineer is implementing VXLAN with a centralized routing gateway. Which TWO statements are correct about BUM traffic handling?

Accepted Answer

Ingress replication sends a copy of the BUM packet to each remote VTEP via unicast. Option B is correct because ingress replication (head-end replication) requires the ingress VTEP to replicate each BUM frame and send a separate unicast copy to every remote VTEP that has interested members, rather than relying on underlay multicast. Option C is correct because this per-VTEP unicast replication multiplies the traffic on the source VTEP's uplinks, consuming more bandwidth than a single multicast stream that the underlay replicates only where needed. Option A is wrong because multicast in the underlay is one valid transport for BUM traffic, but it is not always required since ingress replication is an alternative. Option D is wrong because BUM traffic is flooded to all relevant remote VTEPs, not handled solely by the ingress VTEP. Option E is wrong because BUM traffic is by definition flooded to all VTEPs that participate in the VNI, except the one it arrived from.

Answer

Multicast in the underlay is always required for BUM traffic

Answer

Only the ingress VTEP handles BUM traffic

Answer

BUM traffic is never flooded to all VTEPs

Question 11

An engineer configures vPC on a pair of Nexus switches. The vPC peer-keepalive link fails, but the vPC peer-link remains operational. What is the expected behavior?

Accepted Answer

The vPC domain remains operational with both switches forwarding traffic.. When the vPC peer-keepalive link fails but the peer-link remains up, the vPC domain continues to operate normally because the peer-link is used for control-plane synchronization and data-plane forwarding. The peer-keepalive is only a secondary heartbeat to detect a dual-active scenario when the peer-link is down. Since the peer-link is still functional, both switches can exchange vPC consistency parameters and forward traffic without risk of loops.

Answer

Both switches suspend all vPC member ports to avoid loops.

Answer

The primary switch reloads to prevent a split-brain scenario.

Answer

The secondary switch suspends its vPC member ports.

Question 12

In a VXLAN BGP EVPN fabric, which component is responsible for handling BUM traffic using ingress replication, and how does the VTEP learn the list of remote VTEPs to replicate to?

Accepted Answer

The ingress VTEP learns remote VTEPs via MP-BGP EVPN Type 3 routes.. In a VXLAN BGP EVPN fabric, ingress replication is the default method for handling BUM traffic, where the ingress VTEP replicates packets and sends unicast copies to each remote VTEP. The ingress VTEP learns the list of remote VTEPs from MP-BGP EVPN Type 3 routes (Inclusive Multicast routes), which advertise the VNI and the originating VTEP's IP address, allowing the ingress VTEP to build its replication list.

Answer

The ingress VTEP learns remote VTEPs via IGMP snooping.

Answer

The egress VTEP sends unicast copies to all other VTEPs.

Answer

The spine switch performs replication to all leaf VTEPs.

Question 13

A network engineer is designing a spine-leaf fabric with oversubscription ratio 3:1. Each leaf switch has 48x10G host-facing ports and 4x40G uplinks to spines. What is the oversubscription ratio per leaf?

Accepted Answer

3:1. The oversubscription ratio per leaf is calculated by dividing the total host-facing bandwidth by the total uplink bandwidth. Each leaf has 48x10G host ports (480G total) and 4x40G uplinks (160G total). 480G / 160G = 3:1, matching the design target.

Answer

2:1

Answer

4:1

Answer

1.2:1

Question 14

Which NX-OS feature ensures that vPC member ports on both peers are configured identically to prevent inconsistencies that could lead to traffic black-holing?

Accepted Answer

vPC consistency check. The vPC consistency check ensures that critical parameters (e.g., VLAN configuration, STP settings, interface properties) are identical on both vPC peer switches. If a mismatch is detected, the vPC member port is suspended to prevent traffic black-holing caused by asymmetric forwarding. This mechanism is enforced by the Cisco NX-OS vPC Type-1 and Type-2 consistency checks.

Answer

vPC peer-link

Answer

vPC peer-keepalive

Answer

vPC auto-recovery

Question 15

In an ACI fabric, a contract between two EPGs uses a filter that permits TCP port 443. The provider EPG is configured with a VMM domain integration. Which statement about the contract's effect is true?

Accepted Answer

Traffic from the consumer EPG to the provider EPG on TCP 443 is allowed.. In Cisco ACI, contracts define unidirectional communication from the consumer EPG to the provider EPG. The filter permitting TCP port 443 allows traffic from the consumer to the provider. The VMM domain integration does not alter this contract behavior; it only manages virtual machine connectivity. Therefore, only traffic from the consumer EPG to the provider EPG on TCP 443 is permitted.

Answer

Both directions are allowed for TCP 443.

Answer

Traffic from the provider EPG to the consumer EPG on TCP 443 is allowed.

Answer

The VMM domain overrides the contract and permits all traffic.