Evil Monday dns troubleshoot

Hello, without any change… today my clients and server are unable to get dns…

I always get servfail… in syslog i see that a lot of domains are fetch… but when i try to dig even in the ucs master i cannot get it to resolv the name.

I’m able to ping all dns servers… by ip

From a client if i try query the ucs master i don’t get the server name… and that don’t happen before… any clue?