The correct answer is D.
OSPF and EIGRP use different multicast addresses for exchanging routing information:
* OSPF uses:
* 224.0.0.5 # AllSPFRouters
* 224.0.0.6 # AllDRouters
* EIGRP uses:
* 224.0.0.10
This is a well-known operational difference between the two protocols and is commonly tested in Cisco ENCOR.
* A. OSPF uses IP protocol number 88. EIGRP uses IP protocol number 89. This is reversed.
* EIGRP = IP protocol 88
* OSPF = IP protocol 89
* B. OSPF uses a default hello timer of 5 seconds. EIGRP uses a default hello timer of 10 seconds. This is incorrect.
* On most broadcast and point-to-point networks, OSPF default hello = 10 seconds
* EIGRP default hello = 5 seconds on high-speed links
* C. OSPF uses an administrative distance of 115. EIGRP uses an administrative distance of 160. This is also incorrect.
* OSPF AD = 110
* EIGRP internal AD = 90
* EIGRP external AD = 170
Memorize these protocol identifiers:
* OSPF
* Protocol number: 89
* Multicast: 224.0.0.5 / 224.0.0.6
* EIGRP
* Protocol number: 88
* Multicast: 224.0.0.10