when my friend sign up some site they reply me your ip address is black listed.what is it cause?and what is it solution?any one explain it.

Hi,
web server has it's own security policy. Your IP is blocked by that server. After a period of time it will unblock.

Thank you for sharing.but how many time need for IP address unblock.

Thank you for sharing.but how many time need for IP address unblock.

It's configured at web server.Time depends on server Administrator.