JNCIS-ENT: Juniper Networks Certified Specialist – Enterprise Routing and Switching (2025) — Question 102

Which statement is correct about GRE tunnels?

Answer options

• A. The time-to-live field in the tunnel payload is decremented during transit.
• B. GRE tunnels only support encapsulating non-IP traffic.
• C. There are 20 bytes of overhead with GRE encapsulation.
• D. GRE tunnels only support encapsulating IP traffic.

Correct answer: A

Explanation

The correct answer is A because the time-to-live (TTL) field in the IP header of the GRE payload is indeed decremented as it passes through each router. Option B is incorrect since GRE can encapsulate a variety of protocols, not just non-IP traffic. Option C is inaccurate as GRE encapsulation typically has 24 bytes of overhead, not 20, and option D is wrong because GRE can encapsulate both IP and non-IP protocols.