Term
| What does EIGRP use the hold time for? |
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Definition
| The hold time is the amount of time a router considers a neighbor up without receiving a hello or some other EIGRP packet for that neighbor. |
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Term
| What happens to the hold time on a router when you adjust the hello time away from its default? |
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Definition
| The hold time is not automatically adjusted after a hello interval change. If you change the hello interval, you must manually adjust the hold time to reflect the configured hello interval. |
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Term
| What happens to an adjacency if a packet is not received before the hold time expires? |
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Definition
| If a packet is not received before the expiration of the hold time, the neighbor adjacency is deleted, and all topology table entries learned from that neighbor are removed. |
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Term
| What happens to feasible successors if routes from a specific neighbor are removed? |
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Definition
| The alternate paths, if available, are computed for a new successor. This lets the routes quickly reconverge if an alternative feasible route is available. |
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Term
| How do EIGRP-enabled interfaces use secondary IP addresses? |
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Definition
| EIGRP will not build peer relationships over secondary addresses, because all EIGRP traffic uses the interfaces's primary address. To form an EIGRP adjacency, all neighbors use their primary address as the source IP address for their EIGRP packets. |
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Term
| What command can be used to display the EIGRP IP routing table? |
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Definition
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Term
| What is the smooth round trip timer (SRTT) field in a show ip eigrp neighbors command represent? |
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Definition
| The SRTT times is the average number of milliseconds it takes for an EIGRP packet to be sent to this neighbor and for the local router to receive an acknowledgement of that packet. |
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Term
| What is the retransmit timeout (RTO) field in a show ip eigrp neighbors command represent? |
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Definition
| The amount of time, in milliseconds, that the router waits for an acknowledgement before retransmitting a reliable packet from the retransmission queue to a neighbor. |
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Term
| What type of EIGRP packets use a sequence number in their transmission? |
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Definition
| All packets carrying routing information (update, query, and reply) are sent reliably. This means that a sequence number is assigned to each reliable packet and an explicit acknowledgement is required for that sequence number. |
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Term
| How are reliable multicast packets handled on multiaccess media where multiple neighbors reside? |
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Definition
| Neighbors that are slow to respond to multicasts have the unacknowledged multicast packet retransmitted as unicasts. This allows the reliable multicast operation to proceed without delaying communication with other peers. |
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Term
| What are the different types of routes that are supported by EIGRP? |
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Definition
- Internal - routes that originated within the EIGRP autonomous system - External - routes that are learned from another routing protocol or another EIGRP AS - Summary - routes encompassing multiple subnets |
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Term
| What are the different variables that EIGRP can use to calculate the metric value? |
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Definition
| EIGRP can use bandwidth, delay, reliability, load, and MTU to calculate its metric value. |
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Term
| What variables are used by default to calculate the EIGRP metric value? |
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Definition
| By default, bandwidth and delay are used to calculate the metric value. |
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Term
| How are metrics handled when redistributing routes between IGRP and EIGRP? |
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Definition
| When integrating IGRP routes into an EIGRP domain using redistribution, the router multiplies the IGRP metric by 256. With reverse redistribution, the metric is divided by 256 to get the new IGRP value. |
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Term
| What's the difference between the advertised distance and the feasible distance? |
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Definition
The advertised distance (AD) is the EIGRP metric for an EIGRP neighbor router to reach a particular network. This is the metric between the next-hop neighbor and the destination network. The feasible distance is the EIGRP metric for this router to reach a particular network. |
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Term
| In which table are feasible successor routes stored? |
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Definition
| Feasible successors are kept in the topology table, where it can retain multiple FS routes for a destination. |
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Term
| What is the number 1 requirement for a route to become a feasible successor route? |
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Definition
| A next-hop router must have an AD less than the FD of the current successor route for the particular network. |
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Term
| What command defines the bandwidth for a particular interface? |
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Definition
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Term
| What command is used to configure an EIGRP default route that is used as a last-resort gateway that is announced to other routers? |
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Definition
| ip default-network network-number |
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Term
| How does route summarization work with EIGRP? |
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Definition
| By default, EIGRP automatically summarizes on the major network boundary. But this feature can be turned off. |
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Term
| What is the one requirement when manually creating a summary route using EIGRP? |
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Definition
| EIGRP has added functionality to allow administrators to create one or more summary routes within a network on any bit boundary, but only as long as a more specific route exists in the routing table. |
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Term
| Why does a router set the next-hop interface to null0 for a summary route? |
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Definition
| The use of the null0 interface prevents the router from trying to forward traffic to other routers in search of a more precise, longer match, thus preventing traffic from looping within a network. |
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Term
| What command disables automatic summarization in EIGRP? |
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Definition
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Term
| What command is used to manually create a summary route using EIGRP? |
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Definition
| ip summary-address eigrp as-number address mask [admin-distance] |
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Term
| What is the default number of equal-cost paths that a router will use to load balance traffic? |
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Definition
| By default, IOS will use 4 equal-cost paths for IP |
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Term
| What command changes the number of equal-cost paths used by a router to load balance traffic? |
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Definition
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Term
| How does load balancing differ between process-switched and fast-switched packets? |
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Definition
| When a packet is process-switched, load balancing over equal-cost paths occurs on a per-packet basis. When a packet is fast-switched, load balancing over equal-cost paths is on a per-destination basis. |
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Term
| How does a router load balance traffic that originates from the router? |
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Definition
| Load balancing is preformed only on traffic that passes through the router, not traffic generated by the router. |
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Term
| What command is used to control the degree in which EIGRP preforms load balancing over unequal-cost paths? |
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Definition
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Term
| What command is used to control how traffic is distributed over unequal-cost paths? |
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Definition
| traffic-share [balanced | min across-interfaces] |
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