What exactly is an External Static IP Address?

What Is An External IP Address?

An external IP address is the unique identifier assigned to you by your Internet Service Provider (ISP). There are two types of external IP addresses, static and dynamic. Static is fixed and therefore never changes. Dynamic can change on a regular basis.

Many Internet users, having access through router and running DHCP, experience the same problem - what is the real IP address assigned to them by ISP (Internet Service Provider)? For example, you have a server and you want it to be accessible from outside. So you forward the router port to your local IP and provide the clients with the router external IP address to access the server. If you are lucky, it will work for a long time. If not, then your server may become inaccessible the minute after you set it. The reason: your ISP changed the IP address assigned to you. Your router knows it (and dynamically refreshes all the information required for Internet access) but your clients don’t (and keep hitting the server with an old IP address, wondering why it’s not responding).

Static and Dynamic IP Address inside your Network

A Static IP address is where a computer uses the same address every time, as opposed to situations where the user IP address changes frequently, when a user logs on to a network by dialup or on shared residential cable. Static addressing is essential in some infrastructure situations, such as finding the Domain Name Service directory host that will translate names to numbers.

Static addresses are convenient, but not absolutely necessary, to locate servers inside an enterprise. An address obtained from a DNS server comes with a lifetime argument, after which it should be looked up to confirm that it has not changed. Addresses do change as a result of network administration (RFC 2072).

This contrasts with a Dynamic IP address, wherein an IP address is assigned to a computer, usually by a remote server which is acting as a Dynamic Host Configuration Protocol server. IP addresses assigned using DHCP may change depending on the addresses available in the set scope. Dynamic IP Addresses assigned by Dynamic Host Configuration Protocol servers are used because it reduces the administrative burden of assigning static addresses within a network.

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