How can I tell if an IP address is dynamic?

From Brandonhutchinson.com

Jump to: navigation, search

Overview

Although not a foolproof method, one way to determine if an IP address is dynamic is to look it up in the SORBS Dynamic User List and Host List (DUHL). The DUHL contains most netblocks of dynamically-assigned addresses by ISPs.

Example

As an example, I'll determine if 24.245.33.165 is a dynamic IP by looking it up in the SORBS DUHL.

  • dig method:
$ dig +short 165.33.245.24.dul.dnsbl.sorbs.net
127.0.0.10
  • nslookup method:
nslookup 165.33.245.24.dul.dnsbl.sorbs.netNon-authoritative answer:
Name:   165.33.245.24.dul.dnsbl.sorbs.net
Address: 127.0.0.10

A result of 127.0.0.10 indicates it is in the SORBS DUHL list.

Personal tools