A lot of companies host their sites on shared servers.  This means that multiple web sites share the same IP address.  This is not generally a problem unless you get stuck into what is known as a "bad neighbourhood".  If you are in a bad neighbourhood - it means you are on an IP address with sites that are either spamming, explicit or perhaps have even been banned.  Being in or linking to a "bad neighbourhood" can effect your search engine rankings in engine like Google.

But how can you find out which web sites are also hosted on your same IP address? 

Well Hannah mentioned a tool the other day when she was investigating a situation we had with one of our clients who had been hacked.  She needed to find out what other sites were on the same IP to see if they also had been hacked (they had). 

But if you're in a bind and can't remember that URL, MSN Search offers a search command to do more or less the same thing - "ip:xxx.xxx.xxx.xxx".

So if you wanted to locate all web sites that were also hosted on 212.58.240.32 (the www.bbc.co.uk site).  You would use the following in MSN Live Search.

"ip:215.58.240.32"

Quite handy really.