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Does seeing a different IP address mean I'm seeing a different computer?

I have a friend in Ukraine who uses gotomypc.com for remote access to work
on my computer here in California. Gotomypc records the IP address of each
computer when connected. Is it possible that her connection would cause several
different IP addresses to appear in gotomypc, even though she is operating from
one computer and one connection? Or is that impossible and that different IP
addresses definitely mean different computers?

I hate when I have to say this:

Maybe.

It depends on several things, but most importantly how your Ukrainian friend
is connected to the internet.

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If your friend has been assigned a static IP address by her ISP, then I
would expect to see only that IP address when she connects.

That’s pretty simple, and unfortunately, probably the least likely
scenario.

What’s more likely is that she has what’s called a “dynamic” IP address.
That means that her ISP will automatically assign an IP address to her computer
each time she connects to the internet. That IP address could be the same from
one time to the next, or it could be quite different.

Even if she stays connected continuously, if she’s getting a dynamic IP
address, it can still change. Typically that’s very infrequent, but it’s
completely at the whim of her ISP’s networking equipment.

So is there anything you can tell about the situation?

“..her ISP will automatically assign an IP address to
her computer each time she connects to the internet. That IP address could be
the same from one time to the next, or it could be quite different.”

I’d look at two things: how often you’re seeing a different IP address, and
how close (numerically) those IP addresses are to each other.

Say your friend connects to the internet once a day, and stays connected for
several hours. It’s likely, then, that you should see one IP address each day,
though it might be different from day to day. If she connects and disconnects
10 times a day? Then you might see 10 different IP addresses. If she stays
connected continuously, then I’d personally expect it to change no more than
once a day. It could change more often, but I believe that would be rare.

Regardless of how often the IP address changed, it’d be interesting also to
see if the IP addresses “relate” to one another. For example aaa.bbb.ccc.1 and
aaa.bbb.ccc.2 – addresses that differ only in the lowest number – are likely to
be from the same ISP. On the other hand, IP addresses that differ in the first
number – 1.xxx.yyy.zzz and 2.xxx.yyy.zzz for example – rarely come from the
same provider.

If the timing of the accesses matches your friends access, one additional
concrete step you can take is to visit the ARIN (American Registry for Internet
Numbers) “whois” lookup (whois.arin.net) to
look up the ISP that owns each specific IP address you’re seeing. If they all
belong to the same ISP, then I’d be more confident that the accesses are
probably from the same computer. Certainly if they do not come from
the same ISP, I’d start to get concerned.

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7 comments on “Does seeing a different IP address mean I'm seeing a different computer?”

  1. Actually, the first number of the IP changing with it being the same ISP isn’t so unlikely. For example, they may have a block of IPs between 70.0.0.1 and 72.255.255.255 or something. When my IP changed (it is technically dynamic, but it stays the same for months) it went from 80.xxx.xxx.xxx to 81.xxx.xxx.xxx.

    Reply
  2. True enough, which is why I referenced the ARIN lookup to further validate the source of the IP. But the higher order numbers changing is rare – it’s much more likely that an ISP will assign the same connections out of the same lower order range. As you’ve seen, not impossible, just rare.

    Reply
  3. Hi. But I have another question. What if the IP is the same, but the computer isn’t? For example, the IP is the same, but one time it was a Mac, another a PC? Does it mean it’s the same person in the same building? Could it be another location?

    Reply
  4. I understand about the Ip’s that are static and dynamic. My question is if for example a person lives in Atlanta, can the Ip show up sometimes from Altlanta directly or can it show up sometimes show up as being within close proximity of Atlanta and also can the IP number on tis change even within close proximity? I aks this question because someone i know and know their original Ip adress always or most always showed up as a certain location with the same IP,, however recently i have been getting “views” from places that are suburbs of Atlanta. The reason i ask is that i know no one else within this area, but reently the IP’s numbers have changed, yet still remain similar and are within a near location.

    Depends entirely on the ISP. Possible, but there’s no way to know for sure.

    – Leo
    05-Mar-2009
    Reply
  5. Hi !! Leo–can you please help me to solve this mystery of this case? I had came to know a man a year ago and we kept in touch for almost a year now by emails, smses and phone calls.We had met but we both live in different countries.He lives in California.As I read his emails within this one year, he sent me emails from different IP addresses from Sunnyvale, California to Australia Perth, from Mexico to Houston, from London to Australia Sydney.The whole mystery is he is a handicapped person mobility is impossible for him to move about and staying put in California. So how do one explain the emails he sent to me with completely different IP addresses which literally from other countries?? I am puzzled !!!!PLEASE HELP TO EXPLAIN.

    Reply
  6. Hi Leo,

    I know someone from Texas and he lives there, but when i checked his email header by a website, it said that his IP address is from India, what is that mean? Plz explain to me. Thank you

    Reply
  7. @Bunga
    Are you sure he is in Texas? IP addresses may not pinpoint your exact location but they usually get the country right unless they are sending the email using a proxy. For example, yours tells me you are in Indonesia.

    Reply

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