What does 'key "xxxx" not found in map source' message imply?

Issue

• When cron runs, hundreds of log entries were observed complaining that 'key "xxxx" not found in map source'.

automount[2088]: key "xxxx" not found in map source(s).  
automount[2088]: create_udp_client: hostname lookup failed: Name or service not known  
automount[2088]: create_tcp_client: hostname lookup failed: Name or service not known
automount[2088]: lookup_mount: exports lookup failed for xxxx

OR

• Seen below messages in /var/log/messages, prior to restart :

automount[xxx]: key "IO" not found in map source(s).
automount[xxx]: key "Fcntl" not found in map source(s).
automount[xxx]: key "List" not found in map source(s).
automount[xxx]: key "File" not found in map source(s).
automount[xxx]: key "Compress" not found in map source(s).
automount[xxx]: key "Cwd" not found in map source(s).
yum: Updated: bsh-autofs-files-1.11367-1.noarch