What is TTL in IP packet?

Time to live (TTL) refers to the amount of time or “hops” that a packet is set to exist inside a network before being discarded by a router.

What does a TTL of 1 mean?

When a labeled packet is received with a TTL of 1, the receiving LSR drops the packet and sends an ICMP message “time exceeded” (type 11, code 0) to the originator of the IP packet. This is the same behavior that a router would exhibit with an IP packet that had an expiring TTL.

What is TTL in IP header?

The TTL field, Time To Live, of an IP packet represents the maximum number of IP routers that the packet can go through before being discarded. In current practice you can expect each router on the Internet to decrement the TTL field by exactly one.

What is TTL in a record?

Time To Live, or TTL for short, is the sort of expiration date that is put on a DNS record. The TTL serves to tell the recursive server or local resolver how long it should keep said record in its cache. The longer the TTL, the longer the resolver holds that information in its cache.

What’s the maximum TTL value for an IP packet?

IP packets. The maximum TTL value is 255, the maximum value of a single octet. A recommended initial value is 64. The time-to-live value can be thought of as an upper bound on the time that an IP datagram can exist in an Internet system. The TTL field is set by the sender of the datagram, and reduced by every router on the route to its destination.

What does TTL mean in ICMP Type 11?

TTL indicates the remaining life time of a packet when it is floating on a network. If a packet arrives at a router with TTL Value 1 then that router should discard(as TTL becomes 0) it and send back ICMP Type 11 and Code 0 message(Time to live exceeded).

When is TTL decremented by 1 in IPv4?

According to RFC791 for IPv4 and RFC2460 for IPv6, the TTL value is a decremented by 1 whenever the packet is forwarded by a node. Since the packet is not forwarded when it is passed on to the loopback interface, the TTL is not decremented and a TTL of 1 is sufficient.

What does the TTL mean on a router?

TTL indicates the remaining life time of a packet when it is floating on a network. If a packet arrives at a router with TTL Value 1 then that router should discard (as TTL becomes 0) it and send back ICMP Type 11 and Code 0 message (Time to live exceeded).