If you say Y here (and to one of the following options) and create a
character special file /dev/watchdog with major number 10 and minor
number 130 using mknod ("man mknod"), you will get a watchdog, i.e.:
subsequently opening the file and then failing to write to it for
longer than 1 minute will result in rebooting the machine. This
could be useful for a networked machine that needs to come back
on-line as fast as possible after a lock-up. There's both a watchdog
implementation entirely in software (which can sometimes fail to
reboot the machine) and a driver for hardware watchdog boards, which
are more robust and can also keep track of the temperature inside
your computer. For details, read
Documentation/watchdog/watchdog-api.txt in the kernel source.

The watchdog is usually used together with the watchdog daemon
which is available from
<ftp://ibiblio.org/pub/Linux/system/daemons/watchdog/>. This daemon can
also monitor NFS connections and can reboot the machine when the process
table is full.

If unsure, say N.