DenServ was a Xertion stats bot that logged channels and updated that information every 24 hours.
It has been superseded by Anope 2.0's built-in stats functionality, and therefore no longer exists on the network. To toggle stats functions for your nickname and channel, issue the following commands. Note that these both require you to be identified to your nickname first, and in the case of a channel, that you also have the appropriate access to change a channel's settings:
Turn NickServ stats on/off for your nick:
/msg NickServ set chanstats (on|off)
Turn ChanServ stats on/off for your channel:
/msg ChanServ set chanstats (#channel) (on|off)