312-50V10 · Question #611
What does a type 3 code 13 represent?(Choose two.
The correct answer is B. Destination unreachable D. Administratively prohibited. ICMP Type 3 Code 13 means 'Destination Unreachable - Communication Administratively Prohibited,' indicating a firewall or ACL is actively blocking the traffic.
Question
What does a type 3 code 13 represent?(Choose two.
Options
- AEcho request
- BDestination unreachable
- CNetwork unreachable
- DAdministratively prohibited
- EPort unreachable
- FTime exceeded
How the community answered
(50 responses)- A2% (1)
- B78% (39)
- C4% (2)
- E12% (6)
- F4% (2)
Why each option
ICMP Type 3 Code 13 means 'Destination Unreachable - Communication Administratively Prohibited,' indicating a firewall or ACL is actively blocking the traffic.
Echo request is ICMP Type 8, a completely separate message type used by ping, not Type 3.
ICMP Type 3 is the 'Destination Unreachable' message class defined in RFC 792, used to notify a sender that a datagram could not be delivered for various reasons. All codes within Type 3 are subtypes describing the specific cause of the delivery failure. Code 13 is one such subtype within this class.
Network unreachable is ICMP Type 3 Code 0, not Code 13.
Code 13 within ICMP Type 3 is specifically defined as 'Communication Administratively Prohibited' per RFC 1812, meaning a router ACL or firewall rule rejected the packet. This distinguishes an administrative policy block from routing failures such as network or host unreachable. It directly signals the presence of a packet-filtering policy.
Port unreachable is ICMP Type 3 Code 3, not Code 13.
Time exceeded is ICMP Type 11, an entirely different message type from Type 3 used by TTL expiration.
Concept tested: ICMP Type 3 Code 13 administratively prohibited message meaning
Source: https://www.iana.org/assignments/icmp-parameters/icmp-parameters.xhtml
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