ICMP Type 3 Code 13 Meaning
What does ICMP Type 3/Code 13 mean?
Community Votes
100% of anonymous learners picked answer B. Votes are pick records left by other test-takers — they are not the verified answer.
Community Insight
This question tests knowledge of ICMP destination unreachable codes and the common trap of confusing administrative blocks with host or port unreachability.
ICMP Type 3, Code 13 indicates that a packet was administratively prohibited or blocked. This explanation clarifies the specific meaning of this network forensics indicator.
Candidates often mistake Code 13 for Host Unreachable (Code 1) or Port Unreachable (Code 3) due to similar error categories.
Community Discussion (4 comments)
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Expert Analysis
Why the Answer Is Correct
ICMP Type 3 is designated for 'Destination Unreachable' messages. Within this category, Code 13 specifically signifies 'Communication Administratively Prohibited'. This means the packet was dropped by an intermediate device, such as a firewall or router, due to access control lists (ACLs) or security policies rather than a lack of connectivity.Why the Other Options Are Wrong
Option A (Host Unreachable) corresponds to ICMP Type 3/Code 1, which occurs when a router cannot find a route to the destination network. Option C (Port Unreachable) is ICMP Type 3/Code 3, indicating no application is listening on the target port. Option D (Protocol Unreachable) is ICMP Type 3/Code 2, meaning the IP protocol specified in the header is not supported by the destination host.Community Comment Notes
The community consensus strongly supports Option B. As user 044f354 noted, "Type 3/Code 13 means the packet was administratively filtered or blocked." Another commenter, aqeel1506, explained that this message is used when traffic is blocked due to administrative policies like firewalls.Exam Strategy
Memorize the specific sub-codes for ICMP Type 3 errors. Focus on distinguishing between technical failures (like Host Unreachable) and policy-based drops (Administratively Prohibited), as this distinction is critical for network forensics.
Frequently Asked Questions
What is the difference between Code 1 and Code 13?
Code 1 (Host Unreachable) is a routing failure, while Code 13 (Administratively Prohibited) is a deliberate drop by security policies.
Which ICMP code is for Port Unreachable?
Port Unreachable is ICMP Type 3, Code 3, indicating no service is listening on the destination port.