Helping people with computers... one answer at a time.

I live in Baltimore. When I go to a website the site will often say things like "find sexy singles in Baltimore," and stuff like that. I use spyware software religiously. So how do they know where I live? And how do I get rid of it. These aren't local websites I'm visiting by the way.

Spooky, isn't it? I see the same thing when I visit certain websites. It's not always about "sexy singles", but they frequently nail me down to the Seattle area.

There are a couple of ways this can happen.

The most obvious is one we often overlook.

Ever register with a site? I'll bet at a minimum it required a city, state or postal code. Well, you just told them where you are. That's now information that that site, and possibly other sites operated by the same entity or entities, can use to customize your experience. Including local news, weather, and advertising.

"...it's nearly impossible to physically locate a specific computer based on only its IP address."

The spooky one is where you visit a site for the first time, and up pop those ads for your city.

As I've discussed on other articles, it's nearly impossible to physically locate a specific computer based on only its IP address. The reason is that the publicly available information about IP addresses only resolves down to the ISP that assigned it. If you need to get more detailed, you need the ISP's help.

But, without the ISP's help, you do have something. You have the location of the ISP.

In fact, that's exactly how I get located when I'm at home. Even though I'm located well outside of Seattle, my ISP is based there. Hence ads that use "geo-targeting" based on the IP address resolve to the greater Seattle area.

They can get it wrong, too. The most egregious are cases where they attempt to geo-target an AOL customer. Do a lookup on AOL's IP range, and it "looks like" every AOL customer lives in Manassas, Virginia, regardless of where they really are.

The reality for most lies somewhere in between. As I said, AOL looks like it all originates in one location. Smaller ISPs can typically be located down to the primary metropolitan area that they serve. Some ISPs allocate blocks of IP addresses to specific geographic regions, so that while the ISP might be national, the IP addresses can be geo-targeted to a more specific region. In your case, looking up the IP address you posted from on http://whois.arin.net shows that it's part of a block of IPs that Comcast has allocated to the Baltimore area.

So the bottom line is that advertisers can often, though not always, make a reasonably intelligent guess as to your general location. It's nothing new really, and certainly nothing to be concerned about.

Article C2550 - February 10, 2006 « »

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Leo Leo A. Notenboom has been playing with computers since he was required to take a programming class in 1976. An 18 year career as a programmer at Microsoft soon followed. After "retiring" in 2001, Leo started Ask Leo! in 2003 as a place for answers to common computer and technical questions. More about Leo.

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Recent Comments
20 Comments
Raman
November 27, 2007 9:32 AM

explore this little geo address locator:
http://excathedra.net/Resource/Programming/GeoAddress.aspx

J. Doe
December 18, 2007 12:53 PM

How about: http://www.ip-adress.com/
Using your IP information... pretty damn close I would say.

Leo A. Notenboom
December 20, 2007 10:44 AM

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Hash: SHA1

Oh yeah, only *300 MILES* off for me.

Sorry, but these services are simple NOT reliable and RARELY lead people close
enough to you home for anything significant.

Leo


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LaurieP
April 12, 2008 3:04 PM

I don't think anyone here really knows what they are talking about. When I go on a site for the first time, the ads mention the exact town where I live. My ISP is located over 500 miles from me so the ads are not locking onto my ISP, they know where I am. How is this possible? I saw similar on a chat room where a guests info would include their location and I used to freak people out by guessing correctly where they were, I did't think about privacy at that time. There must be a way to block your info.

LaurieP
April 12, 2008 3:05 PM

I don't think anyone here really knows what they are talking about. When I go on a site for the first time, the ads mention the exact town where I live. My ISP is located over 500 miles from me so the ads are not locking onto my ISP, they know where I am. How is this possible? I saw similar on a chat room where a guests info would include their location and I used to freak people out by "guessing" correctly where they were, I did't think about privacy at that time. There must be a way to block your info.