The transfer attempts and results of ypxfr can be captured in a log file. If a file called /var/yp/ypxfr.log exists, results are appended to it. No attempt to limit the size of the log file is made. To prevent it from growing indefinitely, empty it from time to time by typing the following.
# cd /var/yp# cp ypxfr.log ypxfr.log.old
# cat /dev/null > /var/yp/ypxfr.log