"Last login" message

[Nerius Landys]

When I ssh to my FreeBSD machine, I get something like this:

Last login: Thu Dec  3 15:12:40 2009 from 11.22.33.44
Copyright (c) 1980, 1983, 1986, 1988, 1990, 1991, 1993, 1994
        The Regents of the University of California.  All rights reserved.

FreeBSD 7.1-RELEASE-p9 (DAFFY) #0: Thu Dec  3 11:33:28 PST 2009



..where "11.22.33.44" is an IP address.  However, sometimes, in place
of an IP address I get a truncated hostname, for example
"daffy.nerius.co" (note the last 'm' missing).
I was wondering what controls this, meaning if I get an IP or a
hostname, and why it's being truncated.