ST-CS-10-339-75
March 2002

4.  TTL  (U)

TTL stands for Time To Live.

TTL is the number of a times a packet can be tranfered from one computer to another while en route from its source to its destination, before the packet is regarded as "lost" and is destroyed.

If we consider a computer running Half-life sending a packet out to a server with a TTL of 10, and the packet actually passes through say 15 other computers to reach the server, the tenth computer in the route the packet takes will say "this packet has exceeded it's time to live - I have to dump the packet" and at that point the packet will not be transfered to the eleventh computer but will be destroyed.

The reason this is done is that it is possible for a misconfigured computer to cause a packet to end up performing a loop - never actually reaching its destination. There has to be a mechanism whereby packets will eventually die by themselves.

The word "hop" is used to refer to a packet being transfered from one computer to another.

Any server with a good response will tend to be a low number of hops away, since obviously the more hops there are, the longer the route between the client and server, and the longer it takes the packets sent by the client to reach the server.

Moreover, when playing Counter-Strike, it is generally assumed the client has a decent connection to the server; as such, worrying about whether or not a computer in the route between the client and server is misconfigured is really by the by.

Accordingly, the generally recommended normal value for TTL of 64 is fine for CS.