/* [...] */
Although the T in TTL stands for time, TTL indicates the maximum number of routers (hops) that a packet can pass through before being dropped. Therefore, TTL is not a maximum number of time units.
When a router receives a packet, it decrements the TTL by one before passing it to the next router.
If the TTL reaches 0, it will be dropped, and an icmp Time-to-Live exceeded
error message would be sent to the original sender.
[!note] Some routers are configured not to send such ICMP messages when discarding a packet.