Named issue - Dns stayed offline after reboot for a hour

[kebirhost]

Hello,

There is a interesting named issue in our one of the servers. There are many other servers have same configuration but this server is giving this error.

A few days ago started to get down randomly. It is still getting down in every day. There may be a hardware issue may be RAM issue. Anyway, it can be up by itself in 5-10 minutes but sites do not work because of dns issue. I am checking named as;

ps ax | grep named
service named status

There is no problem at all but sites are giving dns errors. After 1-2 hours, the sites start to work.

I checked all logs and messages are wroted continuosly as;

Jan 11 14:43:51 denge named[25466]: zone forum.pardus-linux.org/IN/internal: sending notifies (serial 2009010800)
Jan 11 14:43:51 denge named[25466]: zone koyturege.com/IN/internal: sending notifies (serial 2009010800)
Jan 11 14:43:52 denge named[25466]: zone alitufekci.av.tr/IN/internal: sending notifies (serial 2009010800)
Jan 11 14:43:53 denge named[25466]: zone fotinovo.com/IN/internal: sending notifies (serial 2009010800)
Jan 11 14:43:55 denge named[25466]: zone karardestek.net/IN/internal: sending notifies (serial 2009010800)
Jan 11 14:43:56 denge named[25466]: zone kimyasanal.info/IN/internal: sending notifies (serial 2009010800)
Jan 11 14:43:57 denge named[25466]: zone akillikart.org/IN/internal: sending notifies (serial 2009010800)
Jan 11 14:43:59 denge named[25466]: zone besalictarim.com/IN/internal: sending notifies (serial 2009010800)
Jan 11 14:43:59 denge named[25466]: zone vipmalatyalilar.com.tr/IN/internal: sending notifies (serial 2009010800)
Jan 11 14:44:01 denge named[25466]: zone 1301217.com/IN/internal: sending notifies (serial 2009010801)
Jan 11 14:44:01 denge named[25466]: zone cevikbicak.com/IN/internal: sending notifies (serial 2009010800)
Jan 11 14:44:04 denge named[25466]: zone fevertanitim.com/IN/internal: sending notifies (serial 2009010800)


I closed the CSF also but no work.

How can we solve the issue?

Thanks.