Check out DALnet's Servers list and connecting to an individual server. Make sure you also try connecting to irc.dal.net. Sometimes when I cannot connect to that address I use mesra.dal.net or slimey.dal.net.

You may also try using another port, such as 6669 or 7000.

If you don't know, the command is:

/server mesra.dal.net 7000 (for example)

Regards,