Free Implementing Cisco Service Provider Advanced Routing Solutions Practice Questions

Sample Practice Questions

Try these 10 sample questions from the Implementing Cisco Service Provider Advanced Routing Solutions practice bank. Each includes the answer and explanation. Continue with the interactive practice above to review the full question set.

1. 1How does ordinary area membership differ between OSPF and IS-IS?

   1. A. OSPF assigns areas to interfaces; an IS-IS router generally belongs to one area.
   2. B. OSPF assigns one area to an entire router; IS-IS assigns an area to each interface.
   3. C. Both protocols require every interface on a router to use the same area.
   4. D. Both protocols require each inter-router link to connect two different areas.

   Answer: A

   Explanation: Cisco states, "In OSPF protocol, any of the router’s interfaces can be assigned to a particular area." For IS-IS, "Here in general, every single router belongs to an Area." The area boundary models therefore differ; they are not interchangeable interface assignments.

   Reference: Configure IS-IS Adjacency and Area Types — IS-IS Areas

2. 2What receiver subscription information distinguishes Source Specific Multicast (SSM) from Any-Source Multicast (ASM)?

   1. A. SSM identifies both source S and group G; ASM group membership accepts any source.
   2. B. SSM identifies only group G; ASM membership always identifies one source S.
   3. C. SSM identifies a multicast MAC address; ASM membership identifies an IP address.
   4. D. SSM identifies a rendezvous point; ASM membership identifies a shortest-path tree.

   Answer: A

   Explanation: Cisco describes SSM subscription as receiving "IP multicast traffic sent by source host S to group G." ASM instead expresses interest in traffic from any source for G. A channel therefore includes source identity, not merely group membership.

   Reference: IP Multicast Technology Overview — PIM Configuration Guide — Source Specific Multicast

3. 3A migration from separately maintained route maps to IOS XR RPL requires one shared filtering block to be maintained centrally and invoked by multiple policies. Which RPL construct provides that modular invocation?

   1. A. A higher route-map sequence number
   2. B. An apply statement referencing a named policy
   3. C. An independent copy of each parent's match statements
   4. D. A prefix-set entry containing the child policy's name

   Answer: B

   Explanation: Cisco states, "the apply command executes another policy" from within a policy. This supports reuse of common blocks; sequence numbers, duplicated text, and data-set elements do not invoke another RPL policy.

   Reference: Cisco ASR 9000 Routing Configuration Guide — Implementing Routing Policy — Policy Statements — apply

4. 4LDP Link Hellos are received across a core link, but an ACL permits UDP and blocks TCP between the peers. Why can discovery work while an LDP session fails?

   1. A. LDP discovery uses TCP, while established sessions use UDP.
   2. B. LDP uses UDP for both discovery and reliable label exchange.
   3. C. Link Hellos use UDP, but session establishment requires TCP.
   4. D. LDP switches from TCP to UDP only after all labels are learned.

   Answer: C

   Explanation: RFC 5036 states, "LDP Link Hellos are sent as UDP packets" and describes an LSR attempting to "open a TCP connection for a new LDP session". Thus the ACL can allow discovery while blocking the session transport.

   Reference: RFC 5036 — LDP Specification — §2.4.1 Basic Discovery Mechanism

5. 5Which IS-IS hierarchy most closely corresponds to OSPF intra-area routing and backbone routing, respectively?

   1. A. Level 2 and Level 1
   2. B. Level 1 and Level 2
   3. C. Level 1-2 and Level 1
   4. D. Level 2 and Level 1-2

   Answer: B

   Explanation: Cisco states, "Level 1 corresponds to OSPF intra-area routing, whereas Level 2 corresponds with the OSPF backbone Area 0 routing." Level 1-2 describes a router participating at both levels, rather than a third routing level.

   Reference: Configure IS-IS Adjacency and Area Types — IS-IS Areas

6. 6Which comparison correctly identifies the roots of multicast source trees and shared trees?

   1. A. Both are rooted at the receiver's designated router.
   2. B. Source trees root at the source; shared trees root at the RP.
   3. C. Source trees root at the RP; shared trees root at each source.
   4. D. Both are rooted at the autonomous-system border router.

   Answer: B

   Explanation: Cisco states, "Unlike source trees that have their root at the source, shared trees use a single common root placed at some chosen point in the network." It identifies that shared root as the RP. Receiver DR and ASBR roles do not define these tree roots.

   Reference: IP Multicast Technology Overview — Cisco White Paper — Shared Trees

7. 7Several route maps differ only in the local-preference value they assign. During conversion to RPL, which design shares the policy logic while allowing each use to supply a different value?

   1. A. A named community-set containing all neighbor addresses
   2. B. A separate hard-coded copy of the policy for every value
   3. C. A parameterized policy receiving the local-preference value
   4. D. A policy-global value that must be identical for every use

   Answer: C

   Explanation: Cisco describes "one common parameterized policy that takes the varying" local-preference value as a parameter. Parameters vary each invocation while sharing logic. A single global value cannot supply different values simultaneously, and copied policies lose the requested reuse.

   Reference: Cisco ASR 9000 Routing Configuration Guide — Implementing Routing Policy — Routing Policy Language Overview — parameterized common blocks

8. 8Two LDP peers receive link Hellos. One advertises its loopback as the transport address, but the other has no route to that loopback. ACLs permit the required transport. Which correction addresses the missing session?

   1. A. Change the FEC label retention mode on both peers.
   2. B. Assign the same local label value to every prefix.
   3. C. Change the multicast destination of the received link Hellos.
   4. D. Restore IP reachability to the advertised transport address.

   Answer: D

   Explanation: RFC 5036 states that the LSR establishes the session by "connecting to the well-known LDP port at address A2." A2 is taken from the advertised Transport Address TLV when present. The peer therefore needs reachability to that address, not merely reception of link-local Hellos.

   Reference: RFC 5036 — LDP Specification — §2.5.2 Transport Connection Establishment, step 3

9. 9A higher-priority router joins each of two stable broadcast LANs, one running OSPF and the other running IS-IS. How do the existing designated-router elections differ?

   1. A. Both protocols immediately replace their existing designated router.
   2. B. OSPF replaces its DR; IS-IS retains its existing DIS.
   3. C. IS-IS replaces its DIS; OSPF does not preempt its existing DR.
   4. D. Neither protocol permits a newly arrived router to take the role.

   Answer: C

   Explanation: Cisco states, "The DIS election is preemptive (unlike OSPF)." It adds, "If a new router boots on the LAN with a higher interface priority, the new router becomes the DIS." Thus the higher priority triggers takeover in IS-IS, but not OSPF.

   Reference: Understanding IS-IS Pseudonode LSP — Election of the DIS

10. 10Compared with maintaining a source tree for every sender, what tradeoff can a shared-tree-only multicast design make?

    1. A. More per-source state in exchange for guaranteed shortest paths
    2. B. No forwarding state in exchange for flooding on every interface
    3. C. Less routing state in exchange for potentially nonoptimal paths
    4. D. Identical routing state in exchange for mandatory source registration removal

    Answer: C

    Explanation: Cisco states, "Shared trees have the advantage of requiring the minimum amount of state in each router." It also says their paths "might not be the optimal paths." Shared trees reduce state but do not guarantee shortest source-to-receiver forwarding.

    Reference: IP Multicast Technology Overview — Cisco White Paper — Source Trees Versus Shared Trees