Man zshparam says, under 'watch,' that '%M' is: 'The full hostname of the
remote host"; and for '%m', says '... If only the IP address is available or
the utmp field contains the name of an X−windows display, the whole name is
printed.

Where I'm using 'watch', only the IP address is given in place of '%M'.
How would it be possible to have it report the actual host name instead of
the IP address?  Does it depend on what's in the utmp or wtmp files?