Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!ucbvax!WLV.IMSD.CONTEL.COM!mcc
From: mcc@WLV.IMSD.CONTEL.COM (Merton Campbell Crockett)
Newsgroups: comp.protocols.tcp-ip
Subject: Re:  traceroute
Message-ID: <8912161455.AA06135@WLV.IMSD.CONTEL.COM>
Date: 16 Dec 89 14:55:30 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 21

Armin:

The record route option is the only way of finding out the exact path that a
packet from point A to point B.  The ICMP packet with the recorded routes may
or may not get back to you.

If you're having problems getting to point B from point A, you can use trace-
route to help identify where your problem might be occurring.  Traceroute uses
an undefined UDP port and the time to live (TTL) header option.  In its default
mode of operation, it transmits its first packet to the destination with a TTL
of one.  It will normally transmit two more packets with the same TTL after an
internal timer expires or after a time exceeded packet is received before
incrementing the TTL value.  For each TTL value it displays the responding
host name and the round trip time for each of the packets transmitted.

Traceroute continues incrementing the TTL until the default maximum of 30 is
reached or until a port unreachable response is received.  At best, you can
infer that this is the path your packets were taking to point B; however, you
may find a different path being reported should you re-initiate traceroute.

Merton