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Thu Sep 18 14:36:54 2008
Name server and Epics
The problems Rob was experiencing last night was due to part of the setup (or rather testing of the setup) of the new nameserver running on linux1.
The name server was setup on linux1 by doing the following:
1) Installed xorg-x11-xauth via yum which was necessary to get remote x windows to work in linux1
2) Installed xorg-x11-fonts-Type1 in order to get the gui system-config-* programs to work
3) Ran system-config-bind, which created a default set of nameserver files. I unfortunately didn't understand the gui all that well, so I manually edited and added files to these base ones. The base files were generated in /var/named/chroot/etc/ and /var/named/chroot/var/named.
4) I added martian.zone and 113.215.131.in-addr.arpa.zone, named.conf.local, and edited named.conf so it loaded named.conf.local. The martian.zone file acts a forward look up (i.e. give it a name and it returns an IP number like 126.96.36.199). The 113.215.131.in-addr.arpa.zone acts as a reverse look up (i.e. give it an IP number like 188.8.131.52 and it tells you the name). The file named.conf.local merely points to these two files.
Note: One can add or change IP lookup by simply updating these two files. The format should be obvious from the files.
5) I specifically ssh'd in as root to linux1 (using su wasn't sufficient) and then typed "service named start" (without quotes). You can also use "restart" or "stop" instead of "start". This started the name server, giving an [Ok] message.
6) I edited the /etc/resolve.conf file on linux1 so that it pointed to itself first ("nameserver 127.0.0.1" at the top of the file). I also added the line "search martian", which allows one to simply use linux1 as opposed to linux1.martian.
I also edited the /etc/resolve/conf file on linux2, and it seems to resolve names fine.
7) And here is where I broke things. As a test, I moved /etc/hosts to /etc/hosts.bak, and then tested to see if names were being resolved correctly. By using the command host, I determined they were in fact working. I also tested with ssh.
However, something basic didn't like me moving the hosts file. Apparently when a front-end machine needed to reboot, it wouldn't come back up, without any ability to SSH or telnet into them.
With Yoichi and I did quite a bit of debugging this morning and determined the nameserver itself isn't conflicting, merely the lack of the host file was the source of the problem. One theory is that services don't know to go to DNS to resolve host names. I think by modifying the /etc/nsswitch.conf file to include dns as an option for services and other programs, it might work without the host file, however, I'm going to leave that to tomorrow morning which is less likely to interfere with current operations.
As it stands, things are working with the nameserver running and the host file in place.