When I try to log into to.ugcs.caltech.edu (without an ssh identity), I get
the following message:

~ % ssh to.ugcs.caltech.edu -l thisuserdoesnotexist 
ssh: to.ugcs.caltech.edu: Name or service not known

again, with the -v flag
~ % ssh -v to.ugcs.caltech.edu -l thisuserdoesnotexist
SSH Version OpenSSH_2.1.1, protocol versions 1.5/2.0.
Compiled with SSL (0x0090581f).
debug: Reading configuration data /home/wtanaka/.ssh/config
debug: Reading configuration data /etc/ssh/ssh_config
debug: Applying options for *
debug: Seeding random number generator
debug: ssh_connect: getuid 2672 geteuid 0 anon 0
ssh: to.ugcs.caltech.edu: Name or service not known

This behavior seems to be independent of the username I pass into ssh, and
independent of whether or not the username exists.

the same binary of ssh works for other sites to which I have attempted
connecting.  (examples:
shell1.sourceforge.net, linux.compile.sourceforge.net)

I could not locate a mirror which had a corresponding SRPM for this
package, and ftp.redhat.com does not seem to let me log in right now.

I ran grep against the 2.2.0p1 (this is a different revision) sourcebase
retrieved from openssh.com, and could not find the error message.