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642-813 Q&A – Implement High Availability (21-25)

Section 5 – Implement High Availability, given a network design and a set of requirements

Refer to the exhibit. What is the configuration an example of?


A. GLBP weighting
B. default AVF and AVG configuration
C. GLBP MD5 authentication
D. GLBP text authentication
E. GLBP timer manipulation
Answer: A
Configuring GLBP Weighting: Example
In the following example, Router A, shown in Figure 1, is configured to track the IP routing state of the POS interface 5/0 and 6/0, an initial GLBP weighting with upper and lower thresholds is set, and a weighting decrement value of 10 is set. If POS interface 5/0 and 6/0 goes down, the weighting value of the router is reduced.
track 1 interface POS 5/0 ip routing
track 2 interface POS 6/0 ip routing
interface fastethernet 0/0
glbp 10 weighting 110 lower 95 upper 105
glbp 10 weighting track 1 decrement 10
glbp 10 weighting track 2 decrement 10
glbp 10 forwarder preempt delay minimum 60

Router R1 and R2 are both configured for HSRP. Which two statements about the HSRP priorities of these two routers are true? (Choose two)
A. To assign the HSRP router priority in a standby group, the standby group-number priority priority-value global configuration command must be used.
B. The default priority of a router is zero (0).
C. The no standby priority command assigns a priority of 100 to the router.
D. Assuming that preempting has also been configured, the router with the lowest priority in an HSRP group would become the active router.
E. When two routers in an HSRP standby group are configured with identical priorities, the router with the highest configured IP address will become the active router.
Answer: CE
HSRP election is based on a priority value (0 to 255) that is configured on each router in the group. By default, the priority is 100. The router with the highest priority value (255 is highest) becomes the active router for the group. If all router priorities are equal or set to the default value, the router with the highest IP address on the HSRP interface becomes the active router.

You want to allow Router R1 to immediately become the active router if its priority is highest than the active router fails. What command would you use if you wanted to configure this?
A. en standby preempt
B. standby preempt enable
C. standby preempt
D. hot standby preempt
Answer: C
The HSRP preemption feature enables the router with highest priority to immediately become the Active router. Priority is determined first by the priority value that you configure, and then by the IP address. In each case a higher value is of greater priority.
When a higher priority router preempts a lower priority router, it sends a coup message. When a lower priority active router receives a coup message or hello message from a higher priority active router, it changes to the speak state and sends a resign message. To configure preemption, use the “standby standby-number preempt” command.

Which type of scheme describes the default operation of Gateway Load Balancing Protocol (GLBP)?
A. per host using a round robin scheme
B. per host using a strict priority scheme
C. per session using a round robin scheme
D. per session using a strict priority scheme
E. per GLBP group using a round robin scheme
F. per GLBP group using a strict priority scheme
Answer: A
The Gateway Load Balancing Protocol feature provides automatic router backup for IP hosts configured with a single default gateway on an IEEE 802.3 LAN. Multiple first hop routers on the LAN combine to offer a single virtual first hop IP router while sharing the IP packet forwarding load. Other routers on the LAN may act as redundant GLBP routers that will become active if any of the existing forwarding routers fail.
GLBP performs a similar, but not identical, function for the user as the HSRP and the VRRP.
HSRP and VRRP protocols allow multiple routers to participate in a virtual router group configured with a virtual IP address. One member is elected to be the active router to forward packets sent to the virtual IP address for the group. The other routers in the group are redundant until the active router fails. These standby routers have unused bandwidth that the protocol is not using. Although multiple virtual router groups can be configured for the same set of routers, the hosts must be configured for different default gateways, which results in an extra administrative burden. GLBP provides load balancing over multiple routers (gateways) using a single virtual IP address and multiple virtual MAC addresses. Each host is configured with the same virtual IP address, and all routers in the virtual router group participate in forwarding packets. In this way, per host load balancing is achieved using a round robin mechanism.

Which first-hop redundancy solution listed would supply Pass4sure clients with MAC address 0000.0C07. AC0A for group 10 in response to an ARP request for a default gateway?
B. Proxy ARP
F. IP Redirects
Answer: D
HSRP is a Cisco-proprietary protocol developed to allow several routers (or multilayer switches) to appear as a single gateway IP address. RFC 2281 describes this protocol in more detail.
Each router keeps a unique MAC address for its interface. This MAC address is always associated with the unique IP address configured on the interface. For the virtual router address, HSRP defines a special MAC address of the form 0000.0c07.acxx, where xx represents the HSRP group number as a two-digit hex value. For example, HSRP Group 1 appears as 0000.0c07.ac01, HSRP Group 16 appears as 0000.0c07.ac10, and so on.