ICMP PING command associated with TTL value. When each hop is reached, the TTL value is reduced by 1. For e.g.
If there are 6 hops to 8.8.8.8.
So a minimum TTL value of 6 is required to reach icmp packets to 8.8.8.8 and get ping replay. And cannot ping to 8.8.8.8 with a TTL value of 5 or less.
Ping Results with different TTL values
[root@server ~]# ping 8.8.8.8 -t 5 (-t 5 is for custom TTL value of 5)
PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
From 192.168.1.1 icmp_seq=1 Time to live exceeded
From 192.168.1.1 icmp_seq=2 Time to live exceeded
From 192.168.1.1 icmp_seq=3 Time to live exceeded
From 192.168.1.1 icmp_seq=4 Time to live exceeded
[root@server ~]# ping 8.8.8.8 -t 6 (-t 6 is for custom TTL value of 6)
PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
64 bytes from 8.8.8.8: icmp_req=1 ttl=55 time=48.9 ms
64 bytes from 8.8.8.8: icmp_req=2 ttl=55 time=49.5 ms
64 bytes from 8.8.8.8: icmp_req=3 ttl=55 time=50.4 ms
64 bytes from 8.8.8.8: icmp_req=4 ttl=55 time=49.4 ms
references:
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