Dynamically Assigned IP Address

What is a Dynamically Assigned IP Address?

Every house in the world has an address. Every telephone has a number. And, every computer that connects to the internet is also assigned a number so that it can be identified by other computers. Imagine trying to call a phone that has no phone number. It just wouldn’t work!

Computer numbers are called IP addresses, which stands for Internet Protocol. The number will be seen as four sets of digits that range from 0 to 255, each separated by a dot. For example The sections of the IP address identify the class of address, the country, and the local network, similar to the way a phone number identifies the country, area code, network, and individual phone. (The system is currently undergoing changes which will allow for many more addresses, due to the explosive growth of the Internet. However, that does not affect the question of static vs dynamic addresses).

There are two ways in which computers are assigned their numbers. The method which is most comparable to the telephone number analogy is that each computer is assigned its own number which is forever associated with that computer. This is called a static IP address. A computer with a static IP address will use that number every time it logs into the Internet. A user does not often need to know the IP address, however the system that makes all the connections work must know it.

The other method in which a computer is assigned a number is by the dynamic IP address method. With dynamic IP addresses, a slightly different number may be assigned to a computer temporarily when it logs onto the Internet. This makes it possible for an Internet service provider to allow for more computers to log on than the number of IP addresses that they own.

Here is how it works. Not all computers are connected to the Internet all the time. When a computer is not connected it does not have to have an IP address. So, a service provider may own a range of similar numbers. If Provider Pete owns, then he has the ability to have 256 computers on line at the same time. However, he might be able to support 1000 customers if no more than a fourth of them are on line at the same time. Each time one of those customers logs in they will be assigned 208.77.188.X, where X is any one of the numbers from 0 to 255 that is not currently logged in.

If a customer of Pete’s logs out and logs back in, even immediately, the chances are that the computer will be assigned a different dynamic IP address for that session. This would never work for telephones, because we are so familiar with using people’s numbers. But, it is a perfect solution for computers because users don’t need to know IP addresses.

In short, static IP addresses are permanently assigned to a computer, while dynamic IP addresses my change from one Internet session to the next. Which type is assigned rarely matters to the average computer user.


Can Someone Trace a Dynamically Assigned IP Address?

To a Smart Phone that sent an email, YES.

Emails sent via a cell phone are no different than any other email.  The phone is a subscriber client to an ISP which delivers the email to the addressee’s email server. Now, Dynamic IP tracing is fairly complicated, the answer depends on many factors, however, smart phone originated email is no different than any other email.

Working definition:  TRACE = Uniquely identify an object of interest with a particular individual (DL#, SSN, POE, TEL #), or determine the geographical location of a single residence or business (25 M accuracy).


Can We Trace a Dynamically Assigned IP Address?

To Zip code accuracy, YES.

·       If landmarks exist on the same sub-net, e.g. the Carrollton Methodist Church or the Roadway Inn of Carrollton, more accurate geographic location becomes possible.

·       If I resolve an address block to and look in the ARIN database I see that it is assigned to Verizon.  At that point Verizon has a procedure where I can get the subscriber by subpoena (civil is fee based, criminal fees and TAT vary).

In general only inside a router ( OSI layer 2, 3) where access to the physical transport layer exists so that the MAC address is exposed.  This is known as ARP, Address Resolution Protocol, which translates physical addresses into logical ( TCP/IP or other addressing protocols).

In more common language, various tools from Ping to packet sniffing can provide this information on a private network.  A private network exists behind a router which routes packets – Your packets turn left, everybody else turn right.  Depending on where this router exists in the communications circuit determines the accuracy of the trace.

My standard example is a server which you can resolve to the router in Verizon’s CO providing the owner as pool-72-64-99-229.dllstx.fios.verizon.net (  I can use a Geo-IP location tool to determine that this address is indeed in Carrollton, more often than not this uses a database lookup rather than triangulation as you would use if you were looking for a radio transmitter.  The reason for this radio travels at the speed of light c, so given three TDOA, time difference of arrival measurements, we can calculate the physical location.  Network TDOA (ping times) are highly dependent on the physical network equipment and the number of hops between point A and B, a very different animal.


Handy FREE Tools:

·       Find your IP address – http://lawrencegoetz.com/programs/ipinfo/

·       Trace a website/URL or IP address – https://www.arin.net/public/

·       Trace a website/URL or IP address – http://cqcounter.com/whois/

·       Trace an IP address – https://geoiptool.com/

·       Trace an IP address – http://www.iplocation.net/

·       Find out how a website has changed or view historical page views – http://archive.org/web/web.php

Author: PDJ Services, Inc.

PDJ Services is a nationwide information brokerage service dedicated to searching and finding people in the US and Canada. Our staff has over 25 years experience in the investigative/people locate trade. PDJ Services is a proud member of national associations as well as many state wide associations.

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