ypxfr 's transfer attempts and the
results 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 entering:
cp /var/yp/ypxfr.log /var/yp/ypxfr.log.old
cat /dev/null > /var/yp/ypxfr.log
You can have crontab execute these commands once a week.
To turn off logging, remove the log file.