What is an IP address?

An IP address is the number that identifies where a device is on a network, so that data sent to it arrives at the right place. Every phone, laptop, printer and server that uses the internet has one, much as every phone on the telephone network has a number.

Names are for people, addresses are for machines

The standard that defines the Internet Protocol (the “IP” in IP address) separates two ideas. A name says what you are looking for. An address says where it is. You type a name such as onlytech.solutions, and your computer has to find the number behind it before it can connect. That lookup is the job of DNS, which is covered in What DNS is, and why your business depends on it.

IPv4 and IPv6

Two versions of the Internet Protocol are in use, and each has its own style of address.

• IPv4 has been in use since 1983 and is still the more common of the two. An IPv4 address is a 32-bit number, written as four numbers separated by dots: 192.0.2.53.
• IPv6 began to be deployed in 1999. An IPv6 address is a 128-bit number, written in groups of letters and digits separated by colons: 2001:0db8:582:ae33::29.

IPv6 exists because the world is running out of IPv4 addresses. Every regional registry has either run out of new IPv4 addresses or is rationing what is left. In the Asia Pacific, the most a member organisation can now receive is 512 of them. The longer IPv6 address leaves room for a far greater number of devices.

Who hands them out

Nobody picks a public IP address for themselves. Addresses are passed down a chain, and each link gets its share from the one above.

1. The Internet Assigned Numbers Authority (IANA) coordinates addresses for the whole world and allocates large pools to five regional registries.
2. The regional registry shares its pool among organisations in its part of the world. For the Asia Pacific that registry is APNIC, which is incorporated in Australia.
3. Internet providers get their addresses from the registry.
4. Your provider assigns an address to your connection.

APNIC deals in numbers only. It does not register domain names, which is a separate system with separate companies.

Why a business should care

The address your provider assigns is how the rest of the internet sees your office. Security equipment uses it too: a firewall can be set to allow or block traffic according to the address it comes from. A supplier who asks for “your IP address” so that they can let your office into their system is asking for this number.

The address comes out of your provider’s allocation, so it stays with the provider. If you change provider, expect the number to change, and expect anything that relied on the old one to need updating.

What to ask

• What is the office’s address on the internet, and where is it written down?
• Does it stay the same, or can the provider change it?
• Which outside systems have been told to trust it?
• Does the provider offer IPv6 on this connection?

The next step is how names are turned into addresses. If nobody in the business can answer the questions above, our network services team can document the connection for you.