Currently I have couple static IPs from my ISP where I host couple websites, my question is if I go to http://www.whoishostingthis.com/ and I check my domain then I get that my ISP is hosting them. How does that work? Thanks
The IPs are registered in name of your ISP as he is allotting IP to you from his own IP range. Have look at Internic website and read more about IP and DNS name registrations.
Even better have a look at Wikipedia article on APNIC. At bottom of page you will find links to articles on ARIN, RIPE NCC, etc. other regional registrars.
That whoishostingthis site dosn't give very good information, and the whole idea of figuring out who hosts a site by looking up their IP address is fundamentally flawed.
The problem is that just because someone is using an IP address doesn't mean they own it. The two IP addresses you're using still belong to your ISP, you're just renting them. So whoishostingthis looks up the IP address for your site, then looks up who owns that IP and reports that as "the host."
Even a fairly big company probably won't "own" its IP addresses, unless it's been around long enough to have its own Class A/B/C network (i.e. it's been around since long before Class A/B/C wnet away...)
It gave bizarre results for my company's domain - on the one hand it correctly said that we host our own site, but OTOH all the links it gives to go to that site were coming up with a totally different domain. I think whoishostingthis is totally misinterpreting our info at ARIN.
Assuming you're in North America (your profile didn't say), you'll want to go and take a look here:
ARIN is the American Registry for Internet Numbers. They're basically the starting point for handing out IP addresses in North America. (Europe, Australia, etc have similar organizations.)
Chances are your ISP was handed an IP block (or got their IP block from a larger ISP).
When you go to the link above and punch in your IP address it will most often show your ISP instead of you.
That being said, if you'd purchased a T1 with half a class C of IP space... there's a good chance that the "big block" would show your ISP and the half a class C you purchased would be in YOUR name.
In most cases, the only way to get YOUR name to show for YOUR IP address is if you have purchased a business connection of some sort.
I recall one time I had an AT&T 1mbps pipe (up and down) with only five IP addresses. AT&T had an online form I filled out and they populated the info from there. They also had a similar form which allowed me to handle my own reverse PTR records.
Most people don't care much about ARIN lookups unless they're trying to get that info OUT of there (ie. trying to be private with a controversial website or something).
I hope this answered your question.