101 · Question #643
An administrator is designing a remote host connection using an ICMP based network troubleshooting utility and receive an ICMP error diagram with the following error code 11. Times exceeded. What…
The correct answer is D. The TTL field of the IP header was decremented to 0. and this was consequently dropped by a. ICMP Type 11 (Time Exceeded) is generated when a router decrements the TTL field of an IP packet to 0 and must discard it. This mechanism prevents packets from looping indefinitely on a network.
Question
An administrator is designing a remote host connection using an ICMP based network troubleshooting utility and receive an ICMP error diagram with the following error code 11. Times exceeded. What does this mean?
Options
- AA faulty router on the network is unable to process the packet in a timely manner
- BA switch on the network the frame due to an incorrect checksum
- CThe TTL field of the IP header was set to 255. and this was consequently dropped by a router
- DThe TTL field of the IP header was decremented to 0. and this was consequently dropped by a
How the community answered
(41 responses)- A2% (1)
- B2% (1)
- D95% (39)
Why each option
ICMP Type 11 (Time Exceeded) is generated when a router decrements the TTL field of an IP packet to 0 and must discard it. This mechanism prevents packets from looping indefinitely on a network.
ICMP Time Exceeded is not related to router processing speed or delays - it is triggered strictly by the TTL counter reaching zero, not by a performance failure.
Incorrect checksums at Layer 2 cause a switch to silently drop the frame without generating any ICMP error message back to the sender.
A TTL value of 255 is simply the maximum initial value and does not cause the packet to be dropped; only reaching 0 triggers the Time Exceeded error.
Each router along a path decrements the TTL field in the IP header by 1. When the TTL reaches 0, the router discards the packet and sends an ICMP Type 11 Time Exceeded message back to the originating host. This is the precise definition of ICMP error code 11 and is the basis of how tools like traceroute map network paths.
Concept tested: ICMP Type 11 Time Exceeded and TTL behavior
Source: https://www.rfc-editor.org/rfc/rfc792
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