Při každém průchodu paketu přes některý uzel tento sníží hodnotu TTL o jedničku.
(článek)
This field must be decreased at each point that the internet header is processed to reflect the time spent processing the datagram. Even if no local information is available on the time actually spent, the field must be decremented by 1. The time is measured in units of seconds (i.e. the value 1 means one second).
