Use the legacy NFS DNS resolver


Linux Kernel Configuration
└─>File systems
└─>Network File Systems
└─>Use the legacy NFS DNS resolver
In linux kernel since version 2.6.36 (release Date: 2010-10-20)  
The kernel now provides a method for translating a host name into an
IP address. Select Y here if you would rather use your own DNS
resolver script.

If unsure, say N