Static Point-To-Point GRE Tunnels CCIE-ENTERPRISE-INFRASTRUCTURE Practice Questions (Page 7)

Questions 31–35

1. 31expert · hard

   A GRE tunnel is configured between two routers. The tunnel interface is up/up, but the engineer cannot ping the remote router's loopback interface that is used as the tunnel destination. The engineer checks the routing table and sees a route to the remote loopback via the physical interface. What is the most likely cause of the ping failure?

   • AThe tunnel keepalive is not configured, so the remote router does not respond to pings.
   • BThe tunnel interface IP address is in the same subnet as the physical interface, causing a conflict.
   • CThe remote router does not have a route back to the local tunnel source IP address.
   • DThe tunnel source is set to the physical interface, but the remote router expects the loopback as the source.
   Reveal Solution Discussion Select an answer first
2. 32expert · hard

   An engineer is designing a GRE tunnel between two sites. The requirement is to carry both IPv4 and IPv6 traffic. The engineer configures the tunnel with an IPv4 address and also enables IPv6 on the tunnel interface. However, IPv6 traffic is not working. What is the most likely cause?

   • AThe tunnel is not configured with an IPv6 address on the tunnel interface, so IPv6 packets cannot be routed into the tunnel.
   • BIPv6 is not supported on GRE tunnels in Cisco IOS.
   • CGRE cannot carry IPv6 traffic; it is only for IPv4.
   • DThe tunnel source and destination must be IPv6 addresses to carry IPv6 traffic.
   Reveal Solution Discussion Select an answer first
4. 33expert · hard

   A GRE tunnel is configured between two routers. The tunnel is up, but the engineer notices that the tunnel interface is receiving a lot of input errors. The engineer checks the physical interface and sees that the MTU is 1500. The tunnel MTU is set to 1476. What is the most likely cause of the input errors?

   • AThe physical interface MTU is too small, causing all packets to be dropped.
   • BThe remote router is sending packets that are larger than the tunnel MTU, causing them to be dropped and counted as input errors.
   • CThe tunnel source and destination are swapped, causing packets to be misrouted.
   • DThe tunnel keepalive is not configured, causing the tunnel to flap and generate errors.
   Reveal Solution Discussion Select an answer first
5. 34expert · hard · select all that apply

   A GRE tunnel is configured between two routers. The tunnel is up/up, but the engineer cannot ping the remote tunnel IP. The engineer has verified that the tunnel source and destination are correct and reachable. Which of the following could be causing the ping failure? (Select all that apply.)

   • AThe tunnel interface on the remote router is administratively down.
   • BThe physical interface on the local router is down, but the tunnel is still up.
   • CThe remote router does not have a route back to the local tunnel source IP.
   • DThe tunnel IP addresses on both ends are in different subnets.
   • EThe local router is not sending keepalives, so the remote router does not respond to pings.
   Check answers Discussion Select an answer first
6. 35application · medium

   After configuring a GRE tunnel between two branch routers, the tunnel interface shows up/up, but users at one branch cannot ping the remote tunnel IP address. The engineer runs a ping from the local router to the remote tunnel IP and it succeeds. What is the most likely cause of the user connectivity failure?

   • AThe MTU on the tunnel interface is too large, preventing user packets from being encapsulated.
   • BThe remote router's tunnel interface is administratively down, but the local router still shows it as up.
   • CThe tunnel is not included in the routing protocol, so user traffic is not being sent into the tunnel.
   • DThe tunnel source and destination are misconfigured, causing intermittent packet loss.
   Reveal Solution Discussion Select an answer first