[CentOS] 2 systems, can't connect to apache on one

I have 2 systems, both with the same version of CentOS installed. Both
have identical versions of apache running and identical httpd.conf
files. From a third system, if I point my browser at system 1, I can
connect to it with no problem. But if I point my browser at system 2,
I cannot connect. There is nothing logged anywhere that I can find on
system 2 - not in the apache error log or access log, or the audit
log, or anywhere. I tried disabling selinux, but that did not help. I
can ping and ssh into system 2, so I know I have a route to it. It's
like the request never reaches the server.

Anyone have any ideas as to what could be causing this or what I could
check to help me diagnose the problem?

TIA!
-larry