Unable to start NFS service

Issue

• Unable to start NFS service on RHEL6, it fails with the following error:

# service nfs restart  
Shutting down NFS mountd: [ FAILED ]  
Shutting down NFS daemon: [ FAILED ]  
Shutting down NFS quotas: [ FAILED ]  
Shutting down NFS services: [ OK ]  
Starting NFS services:[ OK ]  
Starting NFS quotas: Cannot register service: RPC: Unable to receive; errno = Connection refused  
rpc.rquotad: unable to register (RQUOTAPROG, RQUOTAVERS, udp).   [FAILED]  
Starting NFS daemon: rpc.nfsd: writing fd to kernel failed: errno 111 (Connection refused)  
rpc.nfsd: unable to set any sockets for nfsd  [ FAILED ]