Wednesday, January 25, 2006

Static & Dynamic IP Address

This FAQ discusses when you need may Static (or fixed) IP addresses (and how many) and when you can use dynamic IP addresses. IP addresses are in increasingly short supply and like many organizations ZyTrax charges for the use of Static IP addresses. The ZyTrax dynamic IP service 'leases' IP addresses for 24 hours - so you need not worry that 'every time' you connect you will have a different IP address.


As the name implies Static IP addresses are the same every time you connect. dynamic IP addresses may change each time you connect to the network (e.g. Internet).

When you do NOT need static IP addresses

- If you ONLY do things from the following list you do not need static IP addresses.
- If you browse the Internet.
- If you send and receive e-mail via an offsite server (the normal method).
- If you download or upload files.
- If you use Instant message services or chat services.

When you need Static IP Addresses

- You need one or more Static IP addresses if any of the following are true:
- You run one or more Web server's directly on your site that require external access.
- You run one or more E-mail server's directly on your site that require external access.
- You run one or more FTP server's directly on your site that require external access.
- You run any other service or 'Application' that requires external access. Some Financial Terminal Client applications require that you have a static IP address for licensing purposes.
- You allow 'incoming' Video Conferencing you may need to use static IP addresses.

How many IP Addresses do you need

The following 'rules of thumb' apply to calculate the number of required IP addresses.

- If you run one of any type of server (FTP, Web, E-mail etc.) on site then you only require a single Static IP address.
- If you run one copy of any application which uses Fixed Port Numbers you only need a single Static IP address.
- In all other cases you need as many Static IP addresses as there are Applications or Servers that use the same Port Number.
- If you have any doubts discuss then with one of our technical specialists.

Unique IP Address

Your IP address is unique. It's the only one like it in the whole world! Sweet,huh? Your computer can be contacted by any computer on the entire planet that knows your address. Let's see how this works.

In order to provide for an orderly way of tossing bits and bytes of information back and forth between themselves, computers have to have a way of keeping their identities from being confused from any another PC. That's what an IP address does.

An IP address is actually a 32-but number that is expressed as four "octets" which are separated by dots. Here's an example:

Internet Protocol Address

Every time that you visit a web site, send or receive an email, log in to your bank, or even share files with other PCs on your own home or business network, your computer is telling the other computer what its address is and how to find it in cyberspace.

Yep, just like your address is totally unique in that you live in a numbered house or apartment, on a named street, in a named town or city, which is itself in a named county or parish, which is located in a named state, which is part of a named country, on a named continent or island, which happens to be on a named planet, in a named solar system, etc. -- Your computer has a unique address as well. This address is called your Internet Protocol address or IP for short.

What's My IP Address Made Of?

IP addresses consist of four numbers separated by periods. Each one of the four numbers is called an ‘Octet" and look something like There are five IP classes plus certain special addresses with the fifth one being experimental.

IP addresses are assigned by internet service providers (ISP’s) and because they are registered, can be used to track most internet connected computers. IP addresses are often hard to remember, so they are often assigned a Host Name.

What is an IP address?

Every computer connected to the Internet has a unique identifier called an IP address, which consist of four numbers separated by periods (also called a "dotted-quad") and look something like On many networks, the IP address of a computer is always the same. On other networks, a random IP address is assigned each time a computer connects to the network. This is what we are referring to when we ask if you have a static or a dynamic IP address. If a system uses dynamic addressing, the IP can change quite often.

Since these numbers are usually assigned to internet service providers within country-based blocks, an IP address can often be used to identify the country from which a computer is connecting to the Internet. Because the numbers may be tedious to deal with, an IP address may also be assigned to a Host name, which is sometimes easier to remember. Hostnames may be looked up to find IP addresses, and visa-versa.

At one time ISPs issued one IP address to each user. These are called static IP addresses. Because there is a limited number of IP addresses and with increased usage of the internet ISPs now issue IP addresses in a dynamic fashion out of a pool of IP addresses (Using DHCP). These are referred to as dynamic IP addresses. This also limits the ability of the user to host websites, mail servers, ftp servers, and DNS servers. Dynamic DNS services can be used to provide DNS records for servers running on dynamic assigned IP addresses.

In addition to users connecting to the internet, with virtual hosting, a single machine can act like multiple machines (with multiple domain names and IP addresses). An IP address can sometimes be used to determine the user's general location.