Static vs. Dynamic IP addresses...

Dynamic = IP changes
Static = IP never changes

This FAQ discusses when you need may Static (or fixed) IP addresses (and how many) and when you can use dynamic IP addresses. 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.

Definitions

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.

1. If you browse the Internet.
2. If you send and receive e-mail via an offsite server (the normal method).
3. If you download or upload files.
4. 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:

1. You run one or more Web servers directly on your site that requires external access (from the Internet, or Extranet but not typically an Intranet).
2. You run one or more E-mail servers directly on your site that requires external access (from the Internet, or Extranet but not typically an Intranet).
3. You run one or more FTP servers directly on your site that requires external access (from the Internet, or Extranet but not typically an Intranet).
4. You run any other service or 'Application' that requires external access (from the Internet or an Extranet). Some Financial Terminal Client applications require that you have a static IP address for licensing purposes.
5. 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.

1. 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. This is because the Warp Two router allows 'port mapping' for just this situation.
2. If you run one copy of any application which uses Fixed Port Numbers you only need a single Static IP address.
3. In all other cases you need as many Static IP addresses as there are Applications or Servers that use the same Port Number.

Dynamic IP Address

Advantages

1. All the IP configuration information gets automatically configured for your client machine by the DHCP server.
2. If you move your client machine to a different subnet, the client will send out its discover message at boot time and work as usual. However, when you first boot up there you will not be able to get back the IP address you had at your previous location regardless of how little time has passed.

Disadvantage

Your machine name does not change when you get a new IP address. The DNS (Domain Name System) name is associated with your IP address and therefore does change. This only presents a problem if other clients try to access your machine by its DNS name. One example is ftp. If a Windows machine is set up as an ftp server, then its ftp server name (which uses the DNS name) changes every time the IP address does. If you need to use your Windows machine as an ftp server (or as a Web server), request a static IP address rather than a dynamic one.

Static IP Address

Advantages

1. The two names (Windows name and DNS name) are the same as each other, and neither ever changes. Other clients may therefore reliably access your machine by its DNS name (e.g., using ftp).
2. With a static address your machine is more easily accessible by non-Windows internet services. This is not a significant advantage as people seldom telnet to their Windows PC.

Disadvantages

1. You can't move your machine to a different subnet and expect it to work. You need to reconfigure it.
2. If machines come and go, or are up only some of the time, static assignments are less resource-efficient (where the resource in question is the IP address itself).