History of the Internet
The History of DNS: How the Internet Got Names
Computers route packets using numbers, but humans remember names. The Domain Name System is the giant, distributed phone book that translates between the two.
The days of HOSTS.TXT
In the early ARPANET, the mapping from names to addresses lived in a single text file called HOSTS.TXT, maintained by hand at the Stanford Research Institute. Every computer downloaded the same file. When a new host joined, someone edited the master copy and everyone else fetched the update.
This worked for dozens of hosts. It could not possibly work for thousands. The file grew unwieldy, updates lagged, and two sites might request the same name. The internet needed a system that could scale.
The invention of DNS
In 1983, Paul Mockapetris designed the Domain Name System. Its key insight was hierarchy and delegation. Instead of one central list, names are organized as a tree: a root at the top, then top-level domains like .com and .org, then individual domains like example.com, then hosts within them. Authority for each branch is delegated to whoever runs it.
This means no one has to know every name. A resolver asks the root where .com lives, asks the .com servers where example.com lives, and asks example.com's servers for the specific record. Responsibility — and the work — is spread across the whole system.
How a lookup works today
- Your device asks a resolver (often run by your ISP or a public service) for a name.
- The resolver walks the hierarchy: root → top-level domain → authoritative server.
- The answer is cached for a while (its "time to live," or TTL) so repeat lookups are instant.
DNS beyond names
DNS grew to store more than address records. It handles mail routing (MX records), text data used for anti-spam and verification (TXT records), and reverse lookups that map an IP address back to a hostname (PTR records) — the same reverse-DNS lookup that IP Ducky performs to show your connection's hostname. Decades on, DNS remains one of the internet's quietest and most essential systems.