Chapter 8

1:
A:	No further configuration is necessary, because automatic summarization is still enabled at Earhart.
2:
A:	The EIGRP configurations are: RTA routereigrp5 network172.16.0.0 network172.18.0.0 RTB routereigrp5 network172.16.0.0 RTC routereigrp5 network172.16.0.0 network172.17.0.0
3:
A:	This solution uses a key chain named CCIE and key strings named exercise3a and exercise3b . Assuming today's date is November 30, 1998, and the first key begins being used at 8:30 AM, the configurations of the serial interfaces are: keychainCCIE key1 key-stringexercise3a accept-lifetime08:30:00Dec2199808:30:00Jan11999 send-lifetime08:30:00Dec2199808:30:00Jan11999 key2 key-stringexercise3b accept-lifetime08:30:00Jan11999infinite send-lifetime08:30:00Jan11999infinite ! interfaceSerial0 ipaddress172.16.3.19X255.255.255.252 ipauthenticationkey-chaineigrp5CCIE ipauthenticationmodeeigrp5md5
4:
A:	The EIGRP configuration of RTD is: routereigrp5 network172.16.0.0 network172.17.0.0 noauto-summary Auto summarization must also be turned off on RTC.
5:
A:	No changes are needed in the previous EIGRP configurations. The configuration of RTE is: routerigrp5 network172.18.0.0 An identical IGRP configuration is added to RTA. You may also want to use passive-interface statements at RTA.
6:
A:	The EIGRP configuration of RTF is: routereigrp5 network172.16.0.0 network172.18.0.0 noauto-summary The statement ip summary-address eigrp 5 172.18.10.192 255.255.255.224 is added to RTA's interface on subnet 172.18.10.96/27. Also, note that auto-summarization must be turned off on RTA, because of the appearance of the 172.16.0.0 network on RTF.
7:
A:	RTA can send a summary address of 172.16.3.128/25 to RTF and a summary address of 172.16.3.0/25 to RTB. All other summarization is performed automatically.