| 1: || |
If a router does not have a feasible successor, what action will it take?
| A1: || |
If the router does not have a feasible successor in its topology table, it sends a query packet to its neighbors asking whether they have a feasible successor.
| 2: || |
When does EIGRP need to be manually redistributed into another EIGRP process?
| A2: || |
EIGRP needs to be manually redistributed into another EIGRP process when the autonomous system number is different.
| 3: || |
Which timers are tracked in the neighbor table?
| A3: || |
The timers that the neighbor table keeps track of are the holdtime, the SRTT, and the RTO.
| 4: || |
What is the difference between an update and a query?
| A4: || |
An update is the routing information packet that a router will send out to inform its neighbors of a change in the network. In a query, the router has no feasible successor in its topology table for a network that is down. At this point, it queries its neighbors to ascertain whether they have a feasible successor. If they do, this route becomes the feasible successor for the original router.
| 5: || |
When does EIGRP recalculate the topology table?
| A5: || |
EIGRP recalculates the topology table whenever it receives a change input to the topology table. This could be a change of metric for a physically connected link; a change of status of a physically connected link; or an EIGRP routing packet, either an update, a query, or a reply packet.
| 6: || |
EIGRP has a default limit set on the amount of bandwidth that it can use for EIGRP packets. What is the default percentage limit?
| A6: || |
The default percentage limit of bandwidth allocated to EIGRP packets is 50 percent.
| 7: || |
State two rules for designing a scalable EIGRP network.
| A7: || |
The rules for scaling an EIGRP network include the following:
- Allocation of addresses should be contiguous to allow summarization.
- A hierarchical tiered network design should be used to allow summarization.
- Sufficient network resources (both hardware and software) should be used on network devices.
- Sufficient bandwidth should be used on WAN links.
- Appropriate EIGRP configuration should be used on WAN links.
- Filters should be used.
- Network monitoring should be used.
| 8: || |
EIGRP can be used to send information about which three routed protocols?
| A8: || |
EIGRP can be used as a routing protocol for IP, IPX, and AppleTalk.
| 9: || |
Which EIGRP packets are sent reliably?
| A9: || |
The packets that EIGRP sends reliably are updates, queries, and replies. EIGRP uses RTP. This is necessary because EIGRP does not send out periodic updates, and the RTP mechanism ensures a loop-free synchronized network.
| 10: || |
In what instances will EIGRP automatically redistribute?
| A10: || |
EIGRP will automatically redistribute between itself and IGRP as long as both processes are running the same autonomous system number.
EIGRP for IPX automatically redistributes into IPX for RIP/SAP and EIGRP for AppleTalk; it similarly redistributes automatically into RTMP.
| 11: || |
How long is the holdtime, by default?
| A11: || |
The holdtime is three times the Hello timer. The holdtime is 15 seconds or 180 seconds, depending on the medium.
| 12: || |
What is an EIGRP topology table, and what does it contain?
| A12: || |
The topology table contains all links received with a metric other than infinity, that is, every valid path. This will not be all links, because of split horizon. The metric for every path is held along with the metric from the next logical hop or neighbor. The table contains the outgoing interface on the router through which to reach the remote network and the IP address of the next -hop address. The status of the route (passive or active) is also recorded. The topology table also keeps track of the routing protocol packets that have been sent to the neighbors.
| 13: || |
What is the advertised distance in EIGRP, and how is it distinguished from the feasible distance?
| A13: || |
Advertised distance is the metric that is reported by the neighbor routers. Feasible distance is the metric that is reported by neighbor routers, plus the cost associated with the forwarding link from the local interface to the neighbor routers.
| 14: || |
What EIGRP algorithm is run to create entries for the routing table?
| A14: || |
The Diffusing Update Algorithm (DUAL) is run on the topology table. It is used to determine the best path and to build the routing table.
| 15: || |
When does EIGRP place a network in active mode?
| A15: || |
EIGRP places a network into active mode when there is no feasible successor in its topology table.
| 16: || |
By default, EIGRP summarizes at which boundary?
| A16: || |
By default, EIGRP summarizes at autonomous system boundary and at the classful network boundary.
| 17: || |
What is Stuck in Active?
| A17: || |
Stuck in Active (SIA) is a state in which a router will place a route after it has failed to hear a reply to a query that was sent to a neighbor.
EIGRP sends a query when a route is lost and another feasible route does not exist in the topology table. The SIA is caused by two sequential events: First, a route has gone away. Second, an EIGRP neighbor (or neighbors) has not replied to the query for that route. When the SIA occurs, the router clears the neighbor that has not replied to the query. When this happens, it is necessary to determine which neighbor has been cleared, keeping in mind that this router could be many hops away.
| 18: || |
State two factors that influence EIGRP scalability.
| A18: || |
A hierarchical tiered design and contiguous addressing are both critical to being able to scale an EIGRP network. If these are in place, it is possible to summarize the network, which reduces the network resources needed for large tables and limits the query range of the router. It is also important to ensure that the router has sufficient memory, the network has sufficient bandwidth on its WAN links, and, where appropriate, the bandwidth command has been configured.
| 19: || |
What are reply packets in EIGRP?
| A19: || |
The reply packet is used to update the topology table. It is a response to a query sent out by a neighbor asking about suspect routes.
| 20: || |
What conditions must be met for a router to become a neighbor?
| A20: || |
To become a neighbor, the following conditions must be met:
- The router must hear a Hello packet or an ACK from a neighbor.
- The autonomous system number in the packet header must be the same as that of the receiving router.
- The neighbor's k-values and metric settings must be the same as that of the receiving router.