What is a difference between OSPF and EIGRP?

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