You are configuring a GRE tunnel on a router that has multiple physical interfaces. You want the tunnel source to be a specific interface that has a public IP. Which command should you use?

tunnel source GigabitEthernet0/1

tunnel destination GigabitEthernet0/1

A GRE tunnel is up/up, but you cannot ping the remote tunnel IP. You check the routing table and see that the remote tunnel IP is not in the routing table. What is the most likely cause?

The tunnel is not configured with a keepalive.

The physical interface is down.

The remote tunnel IP is not advertised in any routing protocol.

The tunnel source is incorrect.

A GRE tunnel is configured between R1 and R2. The tunnel is up/up, but you cannot ping the remote tunnel IP. You have verified that the tunnel source and destination are correct, and the tunnel IPs are in the same subnet. You also see that the physical interfaces are up. What is the next step to troubleshoot?

Check the tunnel keepalive settings.

Check the MTU on the tunnel interface.

Check the routing table for a route to the remote tunnel IP.

A GRE tunnel is configured to carry both IPv4 and IPv6 traffic. The tunnel is up/up, but IPv6 traffic is not passing. You have verified that IPv6 is enabled on the tunnel interface and that the IPv6 addresses are correct. What is the most likely cause?

The tunnel MTU is too small for IPv6.

The tunnel mode is not set to GRE IPv6.

The IPv6 routing protocol is not configured.

A GRE tunnel is configured between two routers. The tunnel is up/up, but you are experiencing intermittent packet loss. You suspect an MTU issue. You have set the tunnel MTU to 1400, but the problem persists. What is the next best step?

Increase the tunnel MTU to 1500.

Disable the DF bit on the tunnel.

Check the physical path MTU and adjust the tunnel MTU accordingly.

CCIE Enterprise Infrastructure

Domain 3Objective 1

Static Point-To-Point GRE Tunnels CCIE-ENTERPRISE-INFRASTRUCTURE Practice Questions (Page 3)

Part of the Transport Technologies and Solutions domain, which accounts for 15% of the CCIE-ENTERPRISE-INFRASTRUCTURE exam. Cisco does not publish an official question count, but from its 120-minute exam (~50–80 total, ~8–12 in this domain), expect 3–4 from this objective — we provide 42 practice questions to prepare you well beyond it. (estimate)

42questions here

9free pages

4concepts

15%of the exam

Questions 11–15

11application · easy
You are configuring a GRE tunnel on a router that has multiple physical interfaces. You want the tunnel source to be a specific interface that has a public IP. Which command should you use?
Select an answer first
12application · medium
A GRE tunnel is up/up, but you cannot ping the remote tunnel IP. You check the routing table and see that the remote tunnel IP is not in the routing table. What is the most likely cause?
Select an answer first
13expert · hard
A GRE tunnel is configured between R1 and R2. The tunnel is up/up, but you cannot ping the remote tunnel IP. You have verified that the tunnel source and destination are correct, and the tunnel IPs are in the same subnet. You also see that the physical interfaces are up. What is the next step to troubleshoot?
Select an answer first
14expert · hard
A GRE tunnel is configured to carry both IPv4 and IPv6 traffic. The tunnel is up/up, but IPv6 traffic is not passing. You have verified that IPv6 is enabled on the tunnel interface and that the IPv6 addresses are correct. What is the most likely cause?
Select an answer first
15expert · hard
A GRE tunnel is configured between two routers. The tunnel is up/up, but you are experiencing intermittent packet loss. You suspect an MTU issue. You have set the tunnel MTU to 1400, but the problem persists. What is the next best step?
Select an answer first

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