IP Addresses and the Domain Name System

Most of the world takes the Internet for granted. We type a website into our browser or click a link and a website appears like magic. Today, I’m going to take the magic out of the process without drowning you in technical details.

Domain Name System

The domain name system, or DNS, is at the heart of how we use the Internet. When we visit a website, say shadycrzy.com, our Internet browser has to access a special server, a DNS server, which is basically a database with a list of websites (domains) and the IP addresses associated with them.

The Internet Assigned Numbers Authority (IANA) manages 13 root DNS servers around the world which act as the primary address book of the Internet. When we ask the root DNS servers what the IP address of shadycrzy.com is, the root servers will redirect our request to another DNS server with a domain name registry based on the top-level domain (TLD) of the website. The TLD is the last two or three letters of a website (e.g. com, org, uk, mx).

TLDs are managed by both public and private organizations. The .com TLD, for example, is managed by US company Verisign. They are responsible for maintaining the DNS servers that list the IP addresses of every website that ends in .com.

In practice, most residential Internet users will be accessing a DNS server maintained by their Internet service provider (ISP) that makes the process faster for the user and reduces the number of requests to the root servers.

Domain Names

To obtain a domain name (commonly understood as everything that comes before .com and after www.) we usually have to buy one from a domain name registrar. These registrars must be accredited with the parent organization of the IANA, the Internet Corporation for Assigned Names and Numbers (ICANN), for the right to distribute these names to the public.

The domain name registrars (retailers) purchase names from the companies that manage the TLDs (wholesalers). In order to maintain their ICANN accreditation, these registrars must abide by specific rules and procedures in order to maintain the proper functioning of the DNS we discussed earlier.

Because the domain name registrars have to purchase the domain names from different companies based on the TLD, consumers will pay a different price for a .com domain than they would for a .net domain.

IP Addresses

When computers talk to each other, they don’t use words like shadycrzy.com. They use numbers like This number is known as an IP address where IP is short for Internet protocol. Specifically this is an IPv4 (Internet protocol version 4) address. This type of IP address was developed in 1983 and consists of four 8-bit numbers (0 – 255) separated by a period.

Due to the limited potential number of these addresses, and the rapid proliferation of Internet-accessible devices, the last IPv4 address was assigned in 2017. The replacement to the IPv4 addresses are IPv6 addresses, mine (currently) is 2806:102e:1a:5be0:7c68:159c:d473:655a. Quite the mouthful. IPv6 addresses are made up of eight groups of four-digit hexadecimal numbers (16 bits, 0 – 65,535). IPv5 was a thing but it had the same limit on potential numbers as IPv4 and was never widely used.

The ultimate authority on IP addresses is IANA, which we discussed earlier. IANA allocates IP addresses among 5 regional Internet registries (RIRs). These regional registries then distribute their allocated IP addresses to ISPs and other organizations, known as local Internet registries (LIRs). Finally, the LIRs distribute their limited number of IP addresses to their customers as needed.

Putting it all together

When we visit a webpage, we enter the name of a website (domain name) into our browser. Our browser then asks a domain name system server what the address of that website is. The DNS server checks its database of IP addresses for the one associated with the website name, which it returns to our browser, which it can use to request the information directly from the website.

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