Finding out if an IP address is static or dynamic?

Solution 1:

static vs. dynamic is a policy applied by the owner of the IP block. There's no way to determine this reliably unless you have physical access to the IP owner network and can query their DHCP server.

Solution 2:

You could use one of the many DULs (Dialup User Lists). For example,

$ host -t a 1.247.246.70.dul.dnsbl.sorbs.net
1.247.246.70.dul.dnsbl.sorbs.net has address 127.0.0.10

indicates that 70.246.247.1 is in a dynamically-assigned range.

Solution 3:

No, you can't tell if an IP address is static or dynamic. Any time you IP ban a user, you run the risk of banning legitimate users.

If the IP addresses are from out of country, especially from a region that you aren't targeting demographically, I say block away.

If you can prevent automation, that will help a lot in fighting spam, at least enough for your moderators to keep up.

Make sure that you are using the nofollow link attribute when displaying user posted links. This will prevent the spammers from improving their SEO scores in the time it takes to delete the messages.

Many BBs allow you to specify that the user can't post any links until they've posted a minimum number of messages.