I have OS RHNL release 6.2 and use the NFS service (nfs-utils-1.2.3) to connect to NFS server, And found a lot of messages in a file /var/log/messages: Apr 1 11:08:35 XXX rpc.idmapd[3010]: nss_getpwnam: name '2' does not map into domain 'XXXX.com' Apr 1 11:14:26 XXX rpc.idmapd[3010]: nss_getpwnam: name '0' does not map into domain 'XXXX.com' Apr 1 11:18:36 XXX rpc.idmapd[3010]: nss_getpwnam: name '2' does not map into domain 'XXXX.com' Apr 1 11:24:27 XXX rpc.idmapd[3010]: nss_getpwnam: name '0' does not map into domain 'XXXX.com' Apr 1 11:28:37 XXX rpc.idmapd[3010]: nss_getpwnam: name '2' does not map into domain 'XXXX.com' Apr 1 11:34:27 XXX rpc.idmapd[3010]: nss_getpwnam: name '0' does not map into domain 'XXXX.com' Apr 1 11:38:37 XXX rpc.idmapd[3010]: nss_getpwnam: name '2' does not map into domain 'XXXX.com' Apr 1 11:44:28 XXX rpc.idmapd[3010]: nss_getpwnam: name '0' does not map into domain 'XXXX.com' Apr 1 11:48:37 XXX rpc.idmapd[3010]: nss_getpwnam: name '2' does not map into domain 'XXXX.com' What does this message mean ?