Finding out which domains are hosted by an ISP
InternetPeriscope's Whois Tools can help you mine a lot of data from domain names and IP addresses.
In this example, we will use InternetPeriscope to find fifty customers of an ISP.
In this example, our user is investigating an ISP called Monkey Brains, an ISP the author highly recommends. Our user is looking for a new ISP. She has heard good things about this ISP, and wishes to confirm that it has a large customer base.
To begin, our user clicks on the Tools menu, moves her mouse over the "Whois" sub-menu, and then clicks on "Domain Name...", as shown in the figure.
She first needs to find out which servers handle DNS for this ISP. She enters the Second Level Domain Name (SLD) "monkeybrains.net" into the Search String, and clicks on the Search button, as shown in the figure.
Note that she can also use DNS to find out which servers handle DNS for this domain. Use both methods if you are trying to find all the DNS servers for a domain.
The Whois results dialog appears. She scrolls down to where the DNS servers are listed. She holds down the left mouse button while dragging her mouse over the name of one of the DNS servers to select it. She then clicks on the Copy button to copy the name of this DNS server into the clipboard.
She then clicks on the OK button to remove the Whois results dialog. She is returned to the "Search whois.networksolutions.com" dialog. She clicks on the Paste button to paste the DNS server into the Search String text box. She clicks on the Host radio button because she wishes to look up information on this host. Specifically, she wishes to find out the host's handle. Every host in Network Solution's database is given a unique handle. Later, we will use this handle to find out which domains this server handles DNS for.
She again clicks on the Search button.
After a few moments, the Whois results dialog appears, giving the results shown in the figure below. She clicks and drags her mouse over the host's handle, and clicks on the Copy button to copy the host's handle into the clipboard. She then clicks on the OK button to remove the Whois Results dialog.
Back at the "Search whois.networksolutions.com" dialog, she clicks on the Paste button to paste the host's handle into the Search String text box. She clicks on the Server radio button. She clicks on the Summary radio button because she only wants a list of names of domains that are hosted by that server.
She clicks on the Search button to find a list of fifty domains that are hosted by that server.
From here, she may wish to do the following: