I have a frustrating problem occuring on my web/Oracle site. My set up is this:

Oracle 9.2.0.7 back end, web pages generated using PL/SQL (i.e., HTP, HTF
packages), OS is RedHat AS 4.

All networking "appears" to be connected properly. I say "appears" because we no longer have control over that aspect of our network since it was taken over by another group... Anyway, periodically, in the error_log for Apache, we get error messages saying that the mod_plsql module threw an error in this format:

[error] mod_plsql: /pls/inet.home.html HTTP-503 ORA-12545

I know the HTTP-503 means Apache returned a "Service Unavailable" error, and the ORA-12545 is Oracle's way of saying "host not found"...
My first inclination is to say we are having DNS and/or network problems; however, the problem is sporadic and does not occur for all users all the time. Any ideas? We are really getting frustrated with this problem...