Reference Guide

21
ICMP Message Types
This chapter lists and describes the possible ICMP message type resulting from a ping. The first three columns list the
possible symbol or type/code. For example, you would receive a ! or 03 as an echo reply from your ping.
ICMP Messages and Their Definitions.\
Symbol Type Code Description Query Error
. Timeout (no reply)
! 0 3 echo reply .
U 3 destination unreachable:
0 network unreachable .
1 host unreachable .
2 protocol unreachable .
3 port unreachable .
4 fragmentation needed but don’t fragment
bit set
.
5 source route failed .
6 destination network unknown .
7 destination host unknown .
8 source host isolated (obsolete) .
9 destination network administratively
prohibited
.
10 destination host administratively
prohibited
.
11 network unreachable for TOS .
12 host unreachable for TOS .
13 communication administratively
prohibited by filtering
.
14 host precedence violation .
15 precedence cutoff in effect .
C 4 0 source quench .
5 redirect .
0 redirect for network .
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