Free Enterprise Routing and Switching, Specialist (JN0-352) Practice Questions

Sample Practice Questions

Try these 10 sample questions from the Enterprise Routing and Switching, Specialist (JN0-352) practice bank. Each includes the answer and explanation. Continue with the interactive practice above to review the full question set.

1. 1Which field in a received Ethernet frame supplies the address that a switch dynamically learns?

   1. A. The source MAC address
   2. B. The destination MAC address
   3. C. The source IP address
   4. D. The destination IP address

   Answer: A

   Explanation: The guide states, "the switch learns the embedded MAC addresses of the sending nodes". Learning associates the sending node with the receiving interface; destination lookup serves forwarding instead.

   Reference: Bridging and VLANs — Understanding Bridging and VLANs on Switches > How Bridging of VLAN Traffic Works

2. 2How does spanning tree preserve redundant physical paths without creating a Layer 2 forwarding loop?

   1. A. It keeps selected redundant paths in a standby state.
   2. B. It permits every redundant path to forward the same broadcasts.
   3. C. It permanently removes redundant links from possible forwarding.
   4. D. It distributes consecutive frames across every redundant path.

   Answer: A

   Explanation: The guide states, "All other paths are forced into a standby state." These paths remain available for reconvergence rather than forwarding concurrently or being permanently removed. Spanning tree does not provide link-aggregation-style traffic distribution.

   Reference: Spanning Tree Protocol Overview — Spanning Tree Protocols Help Prevent Broadcast Storms

3. 3Which protection disables an edge interface when an unexpected BPDU is received?

   1. A. Loop protection
   2. B. MAC limiting
   3. C. BPDU protection
   4. D. DHCP snooping

   Answer: C

   Explanation: The guide states, "BPDU-block-on-edge disables the interface if the edge ports receive BPDUs." Loop protection addresses missing BPDUs; MAC limiting and DHCP snooping address different attacks.

   Reference: BPDU Protection for Spanning-Tree Protocols — Understanding BPDU Protection for Spanning-Tree Instance Interfaces

4. 4Four otherwise usable static routes to the same prefix differ in route preference. Which preference is selected?

   1. A. Preference 200
   2. B. Preference 100
   3. C. Preference 5
   4. D. Preference 25

   Answer: C

   Explanation: The guide states, "The routes with a lower route preference are always used to route traffic." Five is the lowest preference among these same-prefix candidates.

   Reference: Static Route Preferences and Qualified Next Hops — Understanding Static Route Preferences and Qualified Next Hops

5. 5After OSPF has converged, which information is identical among routers in the same area?

   1. A. Their shortest-path trees rooted at themselves
   2. B. Their individually configured interface addresses
   3. C. Their per-router forwarding next hops
   4. D. Their area topological databases

   Answer: D

   Explanation: The guide states, "Within each area, OSPF routers have identical topological databases." Each router roots its own shortest-path computation at itself, so the computed tree, next hops, and local interface addresses need not be identical.

   Reference: Introduction to OSPF — OSPF Overview > Multiarea Topology

6. 6Which algorithm does IS-IS use to calculate routes from link-state topology information?

   1. A. Spanning-tree root election
   2. B. Shortest-path first
   3. C. BGP best-path selection
   4. D. Distance-vector hop counting

   Answer: B

   Explanation: The overview states, "IS-IS is a link-state IGP that uses the shortest-path-first (SPF) algorithm to determine routes." The other mechanisms concern different protocols or distance-vector routing.

   Reference: IS-IS Overview — IS-IS Overview > Introduction

7. 7Which transport and destination port does BGP use to establish a standard session?

   1. A. UDP port 179
   2. B. TCP port 89
   3. C. UDP port 520
   4. D. TCP port 179

   Answer: D

   Explanation: The overview states, "BGP uses TCP as its transport protocol, using port 179 for establishing connections." UDP and the other port values do not identify a standard BGP connection.

   Reference: BGP Overview — Understanding BGP > Transport

8. 8What logical connectivity does a GRE tunnel create between its endpoint routers?

   1. A. A virtual multipoint link that automatically discovers every remote endpoint
   2. B. A virtual point-to-point connection across the delivery network
   3. C. A physical point-to-point link that replaces the delivery network
   4. D. A shared Layer 2 segment joining the delivery network’s transit interfaces

   Answer: B

   Explanation: The guide says the endpoint routers operate "as if they have a virtual point-to-point connection with each other". GRE uses the routed delivery network; it does not create a physical link, automatically discover a multipoint overlay, or bridge all transit interfaces.

   Reference: Configuring GRE Tunnel Interfaces — Understanding Generic Routing Encapsulation > Overview of GRE

9. 9What does a link aggregation group provide when several physical Ethernet links connect the same logical endpoints?

   1. A. One active link with every other member reserved as standby
   2. B. One logical link with combined bandwidth and member-link redundancy
   3. C. One logical link using only its fastest member for all data
   4. D. Separate logical links managed independently for each physical member

   Answer: B

   Explanation: The guide states, "You can combine multiple physical Ethernet ports to form a logical point-to-point link". Link aggregation combines bandwidth and redistributes traffic among surviving members after a failure; it is not limited to one active or fastest member and is not a collection of independent logical links.

   Reference: High Availability Features for EX Series Switches Overview — Link Aggregation

10. 10A unicast frame arrives on one forwarding port, and its destination has a learned entry on another forwarding port in the same VLAN. What determines the egress port?

    1. A. A lookup of the source IP address
    2. B. A lookup of the destination MAC address
    3. C. A lookup of the source MAC address
    4. D. A lookup of the destination TCP port

    Answer: B

    Explanation: The guide describes "consulting the Ethernet switching table to see whether the table already contains the frame’s destination MAC address". The destination entry selects the known egress interface.

    Reference: Bridging and VLANs — How Bridging of VLAN Traffic Works