I have fixed the above issue by changing my /etc/resolv.config. I have added my univention server DNS in resolv.conf file.
Now I am facing another Problem.
I am trying to integrate the ubuntu to ucs Ad from the following document
In ths Document i have completed the following topics
Integration into the LDAP directory and the SSL certificate authority
Configuration of the System Security Services Daemon (SSSD)
Configuring user logins
When Iam trying to Login It was showing Error Like Invalid Credentials