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What is the difference between dynamic and static IP addresses ?

IP address is a 32-bit number that identifies each client or server on the Internet. This definition is based on the current version 4 of the Internet Protocol (IPv4). Each packet sent across the Internet includes the sender's and receiver's IP addresses in order to route the packets correctly. You can think of it as the Internet equivalent of a phone number where you can be reached. IPv4 addresses are divided into 4 parts, each ranging from 0 to 255, separated by dots, for example:

Dynamic IP addresses can change each time you connect to the Internet, while static IP addresses are reserved for you statically and don't change over time.

Residential Internet connections, whether broadband or dialup usually use dynamic IP addresses, while commercial leased lines and servers have static IPs, so they can always be reached at the same address.

The need for dynamic IP addresses arises from the limited number of IP addresses available in IPv4 (Internet Protocol version 4). Theoretically, there can be about four billion IPs in the Internet, however, the actual number is much lower for various reasons. Something had to be done to ensure supply of address space, at least until IPv6 is widely implemented on the Internet, allowing for 128bit IP addresses. The limited IP address space is one of the reasons for the wide use of NAT routers, as well as DHCP and leasing of dynamic IP addresses.

With dynamic IP addressing, there is a pool of IPs that your ISP can assign to users. When you connect to the Internet, your computer is leased one IP address from that pool for a number of hours. When you disconnect, or when the lease expires the IP address is freed and put back into the pool of available IPs. That way, ISPs can have more subscribers than number of IP addresses (as long as they don't all connect to the Internet at the same time) and ease IP maintenance.

Even with always-on broadband connections, it's easy to just lease IP addresses as needed. That's why the DHCP dynamic IP addressing is widely used today, especially for residential connections where users don't run servers. The downside is, your IP address, or "phone number" if you will, can change any time you get disconnected, there is a power outage, ISP maintenance, etc. The fact that you get disconnected does not necessarily mean the IP address is going to change, just as the fact that you get the same IP address does not mean it is assigned statically.

  User Reviews/Comments:
by Coldstone51 - 2006-02-07 05:54
Thank you. This answered my question and it was like the best one I've read yet. I think that they should introduce the 128 bit IP addresses, but that's just my opinnion, I'm sure others don't think so but what do they know? It is just a matter of time before they have to switch over becuase of how many people are now connecting to the internet and we can only hope that change comes soon. Thank you again for answering my question.
by Patrish - 2006-03-02 23:49
Thank you. I needed clarification on this, and your information was just what I needed. Thanks. Patricia.
by it professional - 2006-07-21 12:53
I found your article to be very resourceful. This was just the clarification i needed regarding the differences between static and dynamic IP adresses and their meanings. Thanks
by anonymous - 2006-08-15 16:31 really was confused about the whole thing until I read this explanation. It's a little incomplete, however. I'd like to hear more about static IPs and how they are important to servers...and why would someone at home with a standard broadband connection want to pay extra for one? Maybe I missed something, but I'd like to hear more about DHCP as well, and how that whole thing works.

great explication though!
by anonymous - 2006-11-09 01:47
I just want to ask if you use a dynamic IP on the internet would it posibly slow your speed? And is a static IP faster because it is assigned to just one user? Thank you
by Philip - 2006-11-09 19:22
No, static IPs are not faster than Dynamic IPs. Static or dynamic, one IP is assigned to one network device or computer. The difference is that statis IP addresses do not change, even if you remain offline for a period of time, while dynamic ones can possibly be released and assigned to someone else.

As for why someone would want to pay more for a static IP address: it is most often used to make running servers on your machine easier, not having to announce every change of your address.
by anonymous - 2007-01-18 06:30
its really good to see many people involving in these discussion forums
by DJ Timmy - 2007-03-04 14:51
Well... After reading that, it explained to me exactly what it is. Thanks, i now have a clear understanding!


DJ Timmy
by mourad marzouk - 2007-10-28 19:31
on a D-link router that is conected to 7 networks and this is done by 7 outs from the router to 7 different closednet each net might have more than 2 PCs but over all nomber i detected are 17 PCs how can i by using the static and dynamic to limit the nomber of pcs at a time as some times they are large nomber and some of them uses applications that grap the speed
by anonymous - 2007-11-14 07:00
I would like to know why when trying to print from a system that is having a DHCP assigned IP to printer using "print to file" the submission location is with static IP machines and the proper source IP is being sent to the printer....need urgent help..
by Sreejith - 2007-11-26 21:09
I have cleared my doubt very well.

Thank for the valuable details

by wade - 2008-12-29 22:30
Thank You,

Explained very clear.
by anonymous - 2009-01-06 13:13
Really it was a very good explanation for me. Since i m an pure ECE, i m not aware of such computer terms(thnks for the excellent explanation)
by faisal - 2009-11-18 00:22
That's cool. expalained well.
by Ernee - 2010-06-13 22:01
Thanks lot. thats what I need.
by Arun Gaur - 2010-10-20 13:51
thanks, very well explained
by joedy - 2011-06-29 21:45
wow, good! but i need the simple explanation about this that i can understand in my part, i think this a same as wireless connection from the source for DYNAMIC IP and wired connection for STATIC IP.
by Aviral - 2011-07-01 21:57
Is there any internet speed difference, when our PC is connected in Static Ip or DHCP setting?
by Philip - 2011-07-28 18:33
There should be no speed difference between a dynamic and static IP address. There may be a slight delay while initially obtaining the IP address depending on how congested the DHCP server is, but that's about it.
by behruz - 2011-08-19 13:16
thanks for excellent explanation, so if we use dynamic ip address we gain ip address from dhcp, do other networks use the same range that we use in our DHCP ??
by anonymous - 2011-08-28 18:54
which is better to use between that static or dynamic when you want to configure server
by Philip - 2011-08-29 07:05
Servers should always be reachable at the same address, so generally they should be assingned static IPs (outside of the dynamic DHCP range).
by tobsinte - 2011-09-01 01:41
Excellent. Very well written so that anyone can easily understand it.
by homegirl - 2011-09-25 23:23
Okay we are a government business/... I need to know what we set our settings to so the outside can get on our server. I am told by a so called Tech that it needs to be set on static except for the router... Is this correct? Please let me know. I am concerned about this.
by anonymous - 2011-11-10 22:37
thank you keep up the good idea'
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