Names and Addresses: DNS and Domains

Every device on a network has a numeric address — a series of numbers that identifies it precisely. When computers talk to each other, they use those numbers. But people don't type numbers into their browsers; they type names like "example.com" or "mycompany.org". Something has to bridge the gap. That something is DNS — the Domain Name System.

DNS is the internet's phone book. When you tap a contact name on your phone, the phone dials the number behind it — you never have to remember the digits. DNS works the same way: you type a name, and DNS silently looks up the numeric address behind it, then your browser connects to that address. The whole lookup happens in milliseconds, and you never see it.

In the cloud, DNS is not just an internet utility — it's the mechanism by which your services get stable, human-friendly names that can point at any server you choose, and be changed at any time without users noticing.

IP Addresses: The Numbers Underneath

An IP address is the numeric label assigned to every device connected to a network. A typical address looks something like 198.51.100.42 — four groups of numbers separated by dots. When your browser connects to a website, it ultimately connects to an IP address like that one. There are billions of devices on the internet, and each has (or shares) a unique address so traffic reaches the right destination. Remembering those numbers for every site would be impossible, which is why names exist.

Domain Names: The Human-Friendly Layer

A domain name — like "bbc.com" or "wikipedia.org" — is a readable label that points to one or more IP addresses. Domain names are registered through a registrar and managed through a system of records that say "this name maps to this address". The name itself is not a server; it's a pointer. The address it points to can be changed, which is why a company can move its website to new servers without changing the name anyone types.

How DNS Works

When you type a domain name into your browser, your computer contacts a DNS resolver — usually one run by your internet provider or a public service. The resolver works its way through a hierarchy of DNS servers to find the authoritative answer: what IP address does this name map to right now? The answer comes back in milliseconds, your browser connects, and the page starts loading. You saw none of this — DNS runs invisibly in the background every time you visit anything online.

One important detail: DNS changes are not instant. When you update a DNS record — say, pointing a domain to a new server — the change takes time to propagate through the resolver network. This can take anywhere from a few minutes to a few hours, depending on how long resolvers are allowed to cache the old answer. Engineers plan for this; it's not a bug, it's how the system works.

DNS in the Cloud

Cloud providers offer managed DNS services that let you create and update DNS records for your own domains from within your cloud account. This is how a company gives its services readable names — "api.mycompany.com" pointing to a load balancer, "admin.mycompany.com" pointing to an internal tool — and updates those pointers as infrastructure changes. AWS's service is called Route 53; Google Cloud's is Cloud DNS; Azure's is Azure DNS. The concept is the same across all three: a managed, programmable phone book that stays in sync with your cloud resources.

You type a namee.g. "example.com"

→

DNS lookupname → address

→

Address returnede.g. 198.51.100.42

→

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