Nokia 4A0-113 Question Answer
What is the protocol number for OSPF in the IP header?
OSPF uses TCP, so the protocol number is 6.
OSPF uses UDP, so the protocol number is 17.
OSPF does not use IP.
OSPF has its own protocol number of 89.
Comprehensive and Detailed Explanation From Exact Extract:
According toNokia 7750 SR OS OSPF Guide — OSPF Packet Transmission Section:
“OSPF is encapsulated directly over IP using protocol number 89. It does not use TCP or UDP.”
TCP (Protocol 6) → Incorrect.
UDP (Protocol 17) → Incorrect.
OSPF operates directly at IP layer using protocol number 89.
Thus, the correct answer isD.
TESTED 02 Jan 2026
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