Telusko Docs

Nobody types 54.221.10.8 into a browser - they type telusko.com. The system that translates the friendly name into the address is DNS, and Route 53 is AWS's DNS service. (The name is a nod to port 53, the port DNS runs on.) It's where you register or manage domains, and where you tell the internet "this name points at that resource."

DNS in one diagram

   You type:  shop.example.com
       │
       ▼
   DNS lookup: "what's the IP for shop.example.com?"
       │
       ▼
   Answer:  13.232.0.50
       │
       ▼
   Browser connects to 13.232.0.50

DNS is the internet's phone book: names in, addresses out. Route 53 is your entry in that phone book, and it's a global service - not tied to a region.

Hosted zones: your domain's container

A hosted zone is a container for all the DNS records of one domain. Create a hosted zone for example.com and inside it you manage every record - www, api, mail, the root, and so on.

   Hosted zone: example.com
   ├── example.com        →  A record  → 13.232.0.50
   ├── www.example.com    →  CNAME     → example.com
   ├── api.example.com    →  A (alias) → load balancer
   └── mail.example.com   →  MX record → mail server

Two kinds:

Public hosted zone - resolves names on the public internet (what a real website uses).
Private hosted zone - resolves names only inside your VPC(s), for internal service names.

The record types that matter

DNS has many record types; you'll use a handful constantly:

Record	Maps a name to	Example
A	An IPv4 address	`example.com → 13.232.0.50`
AAAA	An IPv6 address	`example.com → 2406:da00::1`
CNAME	Another name (alias)	`www.example.com → example.com`
MX	A mail server	routes email for the domain
TXT	Arbitrary text	domain verification, SPF/DKIM
NS	The authoritative name servers	delegation

The A record

The A record is the workhorse: it points a name straight at an IPv4 address. example.com → 13.232.0.50 is an A record. When you "point my domain at my server," you're usually creating or editing an A record.

CNAME vs. A

A CNAME points a name at another name rather than an IP:

   A:     example.com     → 13.232.0.50   (name → IP)
   CNAME: www.example.com → example.com   (name → another name)

A CNAME cannot be used on the root/apex domain (example.com itself) - only on subdomains (www.example.com). This is a hard DNS rule that trips everyone up: you can't CNAME the bare domain. Route 53's answer is the Alias record (below), which can sit on the apex and point at AWS resources.

Alias records: Route 53's superpower

An Alias record is a Route 53-specific record that points a name directly at an AWS resource - a load balancer, CloudFront distribution, S3 website, or another Route 53 record - instead of at a raw IP.

Why it's better than a plain A or CNAME for AWS resources:

It works on the apex domain (unlike CNAME) - so example.com (no www) can point at a load balancer.
It auto-updates if the underlying resource's IP changes (load balancer IPs change; the alias follows).
It's free to query (AWS doesn't charge for alias lookups to AWS resources).

   example.com  ─Alias─►  my-alb-123.ap-south-1.elb.amazonaws.com
   (apex domain pointing straight at the load balancer - no IP to maintain)

This is exactly how you point a domain at a load balancer, which is the next page.

TTL: how long answers are cached

Every record has a TTL (Time To Live) - how long resolvers cache the answer before asking again.

   TTL = 300   → cached for 5 minutes (changes propagate fast, more queries)
   TTL = 86400 → cached for 24 hours  (fewer queries, slow to change)

Lower the TTL before you plan a change (e.g. set it to 60 seconds a day ahead), make the change, then raise it back. That way the old answer expires from caches quickly and your update propagates fast. Forgetting this is why "I changed my DNS but the old site still loads" - caches are still holding the previous answer until its TTL expires. (Alias records to AWS resources sidestep much of this.)

Registering vs. managing a domain

Route 53 does two related jobs - don't confuse them:

Register a domain - buy yourname.com through Route 53 (it's also a registrar). It then auto-creates a hosted zone for you.
Manage DNS for a domain - you can keep a domain bought elsewhere (GoDaddy, Namecheap) and just use Route 53 for DNS. To do that, create a hosted zone, then update the domain's name servers at your registrar to the NS values Route 53 gives you.

   Domain bought at GoDaddy + DNS on Route 53:
     1. Create hosted zone in Route 53 for example.com
     2. Route 53 gives you 4 NS server names
     3. At GoDaddy, set the domain's name servers to those 4
     4. Now Route 53 answers all DNS for example.com

The recap

Route 53 is AWS's global DNS (and a domain registrar).
A hosted zone holds all records for one domain.
A records map names to IPs; CNAMEs map names to other names (not on the apex).
Alias records point names at AWS resources, work on the apex, auto-update, and are free to query - the right choice for load balancers, CloudFront, and S3.
TTL controls caching; lower it before planned changes.

Next, we use all of this to point a real domain at a load balancer.

Route 53 - DNS, Hosted Zones & Records