crookbook 4...

passive interface...

with eigrp if you set an interface to passive you will lose the adjacency on that interface...

r2(config)#router eigrp 1
r2(config-router)#passive-int s2/0
r2(config-router)#
*Sep 30 09:19:48: %DUAL-5-NBRCHANGE: EIGRP-IPv4 1: Neighbor 10.1.1.1 (Serial2/0) is down: interface passive

this might be useful if you want to shut down eigrp, without shutting down the network configuration...

also, using passive-interface default will shut it down for all interfaces, and then you can selectively enable it on a per interface basis with the no passive-interface (interface) command...

offset lists can be used to modify metrics... go for it...

timers:  i see no need changing the defaults... unlike ospf, mismatched timers in eigrp will not take down the adjacency, but expected delivery of hello's to the neighbor will be affected by the set time...

some things are better left alone...

it is no secret that i am not a fan of authentication, however...

r1

key chain suck-key
key 1
key-string suck-key

int s2/0
ip authentication mode eigrp 1 md5
ip authentication key-chain eigrp 1 suck-key

do it on both sides... if you must... of course it is de-testable...