Enhanced Interior Gateway Routing Protocol (EIGRP) Interview Questions and Answers for both Fresher and Experience
Q :- What is EIGRP?Ans :- Is a Distance Vector Routing Protocol (or Hybrid, because uses Link Advertizement thru Hello packets exchange) that provides loop-free networks and fast convergence.
Q :- What Protocol uses and AD?
Ans :- Uses Protocol 88, AD=90 and Summary routes AD=5 External AD=170
Q :- What is the keepalive packet name and what's its timer?
Ans :- Hello Timers: 5s High Bandwidth and 60s Low Bandwidth ; Dead-Timer= 3 times Hello
ip hello-interval eigrp AS secs
ip hold-time eigrp AS secs
Q :- EIGRP Features: Convergence, Bandwidth usage, Subnetting, Load Balancing, Multicasting, Summarization.?
Ans :- Uses very low Bandwidth for reconvergence. By default auto-summary enabled. Uses 224.0.0.10. To sumarize: ip summary-address eigrp [AS] [IP]
Q :- What is Advertisement Distance, Feasible Distance, Successor, Feasible Successor, Passive Route, Active Route.?
Ans :- Adv Dist = The metric as reported by a neighbor. From neighbor to its interface for example.
-Fea Dist = Historical minimum of the best metric
-Successo = The next hop router currently used by this router
-Fea succ = A next hop router that can immediately be used if the primary (successor) fails
-Fea Cond = A condition that states that an advertised distance must be less than the current feassible distance.
Q :- What are the EIGRP Databases?
Ans :- Neighbor table – stores the adjacencies to other routers
-Topology table – entries for each destination
-Routing table – sh ip rou
Q :- EIGRP Packets?
- Ans :- Hello - Sends keepalive and discovers neighbors. Sent as periodic multicast using 224.0.0.10
- Update- Advertize routes when changes ocurr
- Ack - Acknowledgment when an update is received
- Query - Used to querry updates from neighbors
- Reply - Used to answer a query (unicast)
Q :- What is stuck in active SIA?
Ans :- When the Router hasn't received a Reply to a Query.
Q :- How is the Metric calculated?
Ans :- 256*(K1*BW+(K2*BW/(256-L)+K3*D)*K5/R+K4 === K1=1 K2=0 K3=1 K4=0 K5=0 === 256*(BW+D)
BW= Minimum bandwidth
D = Delay
L = Load
R = Reliability
Q :- How to summarize?
Ans :- #int fa0/0
#ip summary-address eigrp (IP) (Subnet) (AD)
Q :- How to do unequal cost load balancing?
Ans :- #variance x
Multiplies x times the value of FD
