CCIE R&S 350-001 Q&As – RIP, VRRP,HSRP,GLBP (16-20)

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Section 11 – RIP, VRRP,HSRP,GLBP

Refer to exhibits 1 and 2. In exhibit 1, all users on the LAN segment use router A as the active HSRP router. Router B is the standby router for the HSRP. In exhibit 2, the network management team reported that there is no utilization on the WAN link B. To solve this problem, you decide to change the logical topology of your LAN, but you are not sure about what changes must be made. You must manage HSRP or change it to another protocol in order to provide the most scalable design, automatic redundancy, and load balancing. Which one of these actions would be the best choice
A.    Use MHSRP, with three users using router A as the default gateway and three users using router B as the default gateway.
B.    Keep HSRP and activate PBR to redirect half of the traffic to the other WAN link.
C.    Use the backup interface on the WAN link B to provide load balancing for all users.
D.    Use GLBP instead, because it provides you with up to three MAC addresses for the same default gateway virtual IP address.
E.    Use GLBP instead, because it provides you with up to four MAC addresses for the same default gateway virtual IP address.
Answer: E

Refer to the exhibit. You are asked to enable redirection for a network optimization engine that will be connected directly to your company CPE. What is the correct configuration to enable redirection for traffic optimization?
A.    (config)#interface s0/0 (config-if)#ip wccp 61 out (config)#interface e0/0 (config-if)#ip wccp 62 out
B.    (config)#interface s0/0 (config-if)#ip wccp 62 in (config)#interface e0/0 (config-if)#ip wccp 61 in
C.    (config)#interface s0/0 (config-if)#ip wccp 61 in (config-if)#ip wccp 62 out
D.    (config)#interface e0/0 (config-if)#ip wccp 61 in (config-if)#ip wccp 62 out
E.    (config)#interface e0/0 (config-if)#ip wccp 61 out (config-if)#ip wccp 62 in
F.    (config)#interface s0/0 (config-if)#ip wccp 61 out (config-if)#ip wccp 62 in
Answer: D
Configuring WCCP for redirection for inbound traffic on interfaces allows you to avoid the overhead associated with CEF forwarding for outbound traffic. Setting an output feature on any interface results in the slower switching path of the feature being taken by all packets arriving at all interfaces. Setting an input feature on an interface results in only those packets arriving at that interface taking the configured feature path; packets arriving at other interfaces will use the faster default path. Configuring WCCP for inbound traffic also allows packets to be classified before the routing table lookup, which translates into faster redirection of packets.

Refer to the exhibit. There are two sites connected across WAN links. All intersite and intrasite links always have the same routing metric. The network administrator sees only the top routers and links being used by hosts at both LAN A and LAN B. What would be two suggestions to load-balance the traffic across both WAN links? (Choose two.)
A.    Make HSRP track interfaces between the edge and core routers.
B.    Replace HSRP with GLBP.
C.    Add crossed intrasite links: R1-R4, R2-R3, R5-R8, and R6-R7.
D.    Make R3 and R8 have lower HSRP priority than R1 and R7.
E.    Replace HSRP with VRRP.
Answer: BC
The administrator sees only the top routers (R1,R2,R5 & R7) and links being used by hosts at both LAN A and LAN B because R1 & R7 are currently active HSRP routers (notice that all the data will need to go through these routers).
Next, all intersite and intrasite links have the same routing metric so these active routers will send packets to R2 or R5, not R3, R4, R6 or R8 because of the lower metric of the top routers. For example, hosts in LAN A want to send
data to hosts in LAN B, they will send data to R1 -> R2 -> R5 -> R7, which has lower metric than the path R1 -> R3 -> R4 -> R6 -> R5 (or R8) -> R7.
To make the network better, we should add crossed intrasite links so that R1 & R7 can send data to both R2/R4 & R5/R6 as they have the same routing metric now -> C is correct.
Cisco Gateway Load Balancing Protocol (GLBP) differs from Cisco Hot Standby Redundancy Protocol (HSRP) and IETF RFC 3768 Virtual Router Redundancy Protocol (VRRP) in that it has the ability to load balance over multiple gateways.
Like HSRP and VRRP an election occurs, but rather than a single active router winning the election, GLBP elects an Active Virtual Gateway (AVG) to assign virtual MAC addresses to each of the other GLBP routers and to assign each network
host to one of the GLBP routers -> B is correct.
Note: The routers that receive this MAC address assignment are known as Active Virtual Forwarders (AVF).

Your Cisco network currently runs OSPF and you have a need to policy-route some specific traffic, regardless of what the routing table shows. Which one of these options would enable you to policy-route the traffic?
A.    source IP address and the protocol (such as SSL, HTTPS, SSH)
B.    the packet Time to Live and the source IP address
C.    type of service header and DSCP value
D.    destination IP address
Answer: A
Policy-based routing (PBR) provides a mechanism for expressing and implementing forwarding/routing of data packets based on the policies defined by the network administrators. It provides a more flexible mechanism for routing packets through routers, complementing the existing mechanism provided by routing protocols.
Routers forward packets to the destination addresses based on information from static routes or dynamic routing protocols such as Routing Information Protocol (RIP), Open Shortest Path First (OSPF), or Enhanced Interior Gateway Routing Protocol (Enhanced IGRP?). Instead of routing by the destination address, policy-based routing allows network administrators to determine and implement routing policies to allow or deny paths based on the following:
-Identity of a particular end system
-Size of packets

Which one of the following potential issues is eliminated by using split horizon?
A.    Joined horizons
B.    Packet forwarding loops
C.    cisco Express Forwarding load-balancing inconsistency
D.    Asymmetric routing throughout the network
Answer: B
Split horizon is a base technique used to reduce the chance of routing loops. Split horizon states that it is never useful to send information about a route back in the direction from which the information came and therefore routing information should not be sent back to the source from which it came. In fact, only the interfaces are considered for the direction, not the neighbors.
Note that this rule works well not only for routes learned via a distance vector routing protocol but also for routes installed in a routing table as directly connected networks. As they reside on the same network, the neighbors do not need any advertisements on a path to that shared network.
The split horizon rule helps prevent two-node (two-neighbor) routing loops and also improves performance by eliminating unnecessary updates.