+.I nfsidmap
+can also used to clear the keyring of all the keys.
+This is useful when all the mappings have failed to due to an DNS outage
+or some other error resulting in all the cached uid/gid to be invalid.
+.SH OPTIONS
+.TP
+.B -c
+Clear the keyring of all the keys.
+.TP
+.B -t timeout
+Set the expiration timer, in seconds, on the key.
+The default is 600 seconds (10 mins).
+.TP
+.B -v
+Increases the verbosity of the output to syslog
+(can be specified multiple times).