basic questions

It was suposed to be reduced by AT LEAST 1 per hop, and was suposed to be measured in seconds, but in pratice, each hop is 1 click off the TTL. In IPv6 they renamed it like hop count or something too.

yeah, i thought so. almost all computer books define TTL and none ever mention anything about the 1 second deal. Must not be a really good book. But then it upsets me that the professor covered this topic and didn't express his disagreement with the statement.

TTL is time to live: you may think it as time to live (number of seconds) but actually it is number of hops. This parameter is used to remove the packet from the network if it is failed to reach the destination.

For example:
ping 10.0.22.226 -i 2

here TTL is set to 2 ( default is 64 for windows). so if the above host is reachable by 2 hop, then it will get the ping reply with number of hops it took to reach the destination!!

else you will get message like:
Reply from 10.0.22.226: TTL expired in transit.

This is a very important parameter for ICMP protocol

That doesn't sound right to me. How would router 2 know what time the packet left router 1? Unless I'm missing something about regular data packets having timestamps in them...

Hmm, what if the router timestamped the packets only internally? could that be possible?

Negative.

TTL is the maximum of hops a package can travel.
Time is of no importance (besides timeout ofcourse )

That doesn't sound right to me. How would router 2 know what time the packet left router 1? Unless I'm missing something about regular data packets having timestamps in them...

Hmm, what if the router timestamped the packets only internally? could that be possible?

Again, how would other routers know this time if its only internally ?