Edit /etc/resolv.conf and ensure that the entries are similar to the following:
nameserver server 1 IP address nameserver name server 2 IP address nameserver name server 3 IP address domain your-domain-name search your-domain-name
For example, assume the IP address of the first DNS server is 129.123.111.12, the second DNS server is 129.123.111.24, and the third DNS server is 129.123.111.36. If your company domain name is mydomain.com, then the /etc/resolv.conf file would contain the following lines.
nameserver 129.123.111.12 nameserver name 129.123.111.24 nameserver name 129.123.111.36 domain mydomain.com search mydomain.com