Q1. Which two events occur when a packet is decapsulated in a GRE tunnel? (Choose two.)
A. The destination IPv4 address in the IPv4 payload is used to forward the packet.
B. The TTL of the payload packet is decremented.
C. The source IPv4 address in the IPv4 payload is used to forward the packet.
D. The TTL of the payload packet is incremented.
E. The version field in the GRE header is incremented.
F. The GRE keepalive mechanism is reset.
Answer: A,B
Explanation:
After the GRE encapsulated packet reaches the remote tunnel endpoint router, the GRE packet is decapsulated. The destination address lookup of the outer IP header (this is the same as the tunnel destination address) will find a local address (receive) entry on the ingress line card. The first step in GRE decapsulation is to qualify the tunnel endpoint, before admitting the GRE packet into the router, based on the combination of tunnel source (the same as source IP address of outer IP header) and tunnel destination (the same as destination IP address of outer IP header). If the received packet fails tunnel admittance qualification check, the packet is dropped by the decapsulation router. On successful tunnel admittance check, the decapsulation strips the outer IP and GRE header off the packet, then starts processing the inner payload packet as a regular packet. When a tunnel endpoint decapsulates a GRE packet, which has an IPv4/IPv6 packet as the payload, the destination address in the IPv4/IPv6 payload packet header is used to forward the packet, and the TTL of the payload packet is decremented.
Reference: http://www.cisco.com/c/en/us/td/docs/routers/asr9000/software/asr9k_r5-3/addr-serv/configuration/guide/b-ipaddr-cg53asr9k/b-ipaddr-cg53asr9k_chapter_01001.html
Q2. DRAG DROP
Drag and drop the BGP attribute on the left to the correct category on the right.
Answer:
Q3. Which two types of traffic are blocked when the storm control threshold for multicast traffic is reached on a port? (Choose two.)
A. BPDU
B. OSPF
C. CDP
D. IS-IS
E. LLDP
Answer: B,D
Q4. In the DiffServ model, which class represents the highest priority with the lowest drop probability?
A. AF11
B. AF13
C. AF41
D. AF43
Answer: C
Q5. DRAG DROP
Drag and drop each BGP feature on the left to the corresponding function it performs on the right.
Answer:
Q6. In which two situations is an EIGRP hello packet sent as unicast? (Choose two.)
A. during neighbor discovery
B. when link costs change
C. when the neighbor command is used
D. when an ACK is sent
Answer: C,D
Q7. Refer to the exhibit.
Which statement is true?
A. IS-IS has been enabled on R4 for IPv6, single-topology.
B. IS-IS has been enabled on R4 for IPv6, multitopology.
C. IS-IS has been enabled on R4 for IPv6, single-topology and multitopology.
D. R4 advertises IPv6 prefixes, but it does not forward IPv6 traffic, because the protocol has not been enabled under router IS-IS.
Answer: A
Explanation:
When working with IPv6 prefixes in IS-IS, you can configure IS-IS to be in a single topology for both IPv4 and IPv6 or to run different topologies for IPv4 and IPv6. By default, IS-IS works in single-topology mode when activating IPv4 and IPv6. This means that the IS-IS topology will be built based on IS Reachability TLVs. When the base topology is built, then IPv4 prefixes (IP Reachability TLV) and IPv6 prefixes (IPv6 Reachability TLV) are added to each node as leaves, without checking if there is IPv6 connectivity between nodes.
Reference: https://blog.initialdraft.com/archives/3381/
Q8. Which two features improve BGP convergence? (Choose two.)
A. next-hop address tracking
B. additional paths
C. advertise map
D. communities
E. soft reconfiguration
Answer: A,B
Explanation:
The BGP Support for Next-Hop Address Tracking feature is enabled by default when a supporting Cisco software image is installed. BGP next-hop address tracking is event driven. BGP prefixes are automatically tracked as peering sessions are established. Next-hop changes are rapidly reported to the BGP routing process as they are updated in the RIB. This optimization improves overall BGP convergence by reducing the response time to next-hop changes for routes installed in the RIB. When a best path calculation is run in between BGP scanner cycles, only next-hop changes are tracked and processed. BGP routers and route reflectors (RRs) propagate only their best path over their sessions. The advertisement of a prefix replaces the previous announcement of that prefix (this behavior is known as an implicit withdraw). The implicit withdraw can achieve better scaling, but at the cost of path diversity. Path hiding can prevent efficient use of BGP multipath, prevent hitless planned maintenance, and can lead to MED oscillations and suboptimal hot-potato routing. Upon nexthop failures, path hiding also inhibits fast and local recovery because the network has to wait for BGP control plane convergence to restore traffic. The BGP Additional Paths feature provides a generic way of offering path diversity; the Best External or Best Internal features offer path diversity only in limited scenarios. The BGP Additional Paths feature provides a way for multiple paths for the same prefix to be advertised without the new paths implicitly replacing the previous paths. Thus, path diversity is achieved instead of path hiding.
References: http://www.cisco.com/en/US/docs/ios-xml/ios/iproute_bgp/configuration/15-1sg/irg-nexthop-track.html http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/iproute_bgp/configuration/xe-3s/irg-xe-3s-book/bgp_additional_paths.html
Q9. Refer to the exhibit.
With these configurations for R1 and R2, which statement about PPP authentication is true?
A. Authentication fails because R1 is missing a username and password.
B. R2 responds with the correct authentication credentials.
C. R2 requires authentication from R1.
D. R1 requires authentication from R2.
Answer: C
Explanation:
Only R2 is configured with the “PPP authentication PAP” command so it requires authentication from R1, but R1 does not require authentication from R2.
Q10. DRAG DROP
Drag and drop the multiprotocol BGP feature on the left to the corresponding description on the right.
Answer: