Every domain name is a position in a tree. Read shop.yourbusiness.co.in from right to left and you walk down that tree: from the root, to the .in extension, to .co.in, to your name, to a subdomain you created. This guide explains each level, who controls it, and why the structure matters when you register a domain or set up DNS.
The Domain Name System is a hierarchy: the root at the top, top-level domains such as .in and .com below it, then second-level names, then any number of subdomains. Each level is controlled by a different party, and each can hand control of the level below to someone else. When you register yourbusiness.in, the .in registry delegates that name to you, and everything under it, such as www or shop, is yours to create for free.
1. The hierarchy at a glance
A domain name is a series of labels separated by dots. Each label is one level of the tree, and the level of a label is counted from the right.
| Level | In shop.yourbusiness.co.in | Who controls it |
|---|---|---|
| Root | the invisible final dot | IANA, which maintains the root zone, coordinated by ICANN |
| Top-level domain (TLD) | in | The .in registry, operated under NIXI |
| Second level | co | The .in registry (a registry-run extension, .co.in) |
| Third level | yourbusiness | You, the registrant, through your registrar |
| Fourth level | shop | You: a subdomain you create at no cost |
For a name like yourbusiness.in, "yourbusiness" is the second level. Under .co.in, .org.in and similar extensions, the name you register sits one level lower, but in practice it works exactly the same way. How do domain names work calls .co.in a "second-level extension" for this reason.
2. The root
The root sits above every TLD. It is written as a single dot, which browsers hide: yourbusiness.in. with the trailing dot is the fully qualified form of yourbusiness.in. In DNS zone files that trailing dot matters, because a name without it is treated as relative to the zone.
The root zone lists every TLD and the nameservers for each. It is served by 13 named root server identities (a.root-servers.net to m.root-servers.net), run by 12 independent organisations, with well over a thousand copies spread around the world through anycast. Every DNS lookup that is not already cached starts here.
3. Top-level domains
TLDs are the level just below the root. The main groups are:
A registry runs each TLD and keeps the master list of names under it, with the nameservers for each. It does not store your website's address; that lives on your nameservers. Benefits and drawbacks of different gTLDs compares the common choices.
4. Second-level domains and registry extensions
The second level is where most people register: example.com, yourbusiness.in. The label must be unique within its TLD, which is why example.com and example.in can belong to different owners.
Some registries also offer their own second-level extensions under the TLD. India has .co.in, .net.in, .org.in, .firm.in, .gen.in, .ind.in and others. The UK uses .co.uk in the same way. These behave like TLDs for registration: you register yourbusiness.co.in from a registrar, and nobody else can create names under it.
Browsers keep a list of "public suffixes": endings under which anyone can register, such as .in, .co.in and .com. It stops a site at a.co.in from setting cookies for every .co.in website. It is also why tools treat yourbusiness.co.in as your whole domain, not as a subdomain of co.in.
5. Subdomains: the levels you create
Everything below your registered name is yours. You create subdomains by adding DNS records, with no extra registration or fee:
www.yourbusiness.in, the conventional website address;mail.yourbusiness.infor email services;shop.yourbusiness.inorblog.yourbusiness.infor a separate part of the site;dev.shop.yourbusiness.in, a deeper level for testing.
A subdomain can point to the same server as the main site or to a completely different one. On a hosting account, you usually create subdomains in the control panel, which adds the DNS record and a folder for the files. Your plan may limit how many you can create. Parked, addon and subdomains explains the difference between the three.
6. Delegation: how control passes down the tree
Each level can delegate a name to someone else by publishing NS (nameserver) records for it:
- The root delegates .into the .in registry's nameservers.
- The .in registry delegates yourbusiness.into the nameservers your registrar sent when you registered or changed them.
- Your nameservers answer for everything below, such as
wwwandshop, from the records in your DNS zone. - Optionally, you delegate a subdomainsuch as
app.yourbusiness.into another provider's nameservers, so that provider manages it separately.
This chain is also how a lookup travels: a resolver asks the root, is referred to .in, is referred to your nameservers, and gets the answer there. What is a nameserver and why do I need it covers the practical side.
7. Rules for names at every level
- A label may use letters, digits and hyphens, and may not start or end with a hyphen.
- Each label can be up to 63 characters, and the whole name up to 253 characters.
- Names are not case-sensitive:
YourBusiness.INandyourbusiness.inare the same. - Names in Indian and other scripts are stored in an ASCII form beginning
xn--(Punycode) and shown in their own script by browsers.
8. Why the hierarchy matters to you
- Uniqueness: a name can only be registered once in its extension, so your address points to you alone.
- Independence: you manage your own subdomains without asking the registry.
- Resilience: no single server holds every record; each level answers only for its own part.
- Flexibility: you can move the website, the email and any subdomain to different providers independently, by changing records or delegating.
9. Domain India and your place in the hierarchy
Domain India is a NIXI-accredited .IN registrar. When you register a .in-family domain with us, we pass the registration and your nameservers to the .in registry, and the second or third level becomes yours. Domain India list prices on 19 September 2026, excluding 18% GST:
| Extension | Register (1 year) | Renew (per year) |
|---|---|---|
| .in | ₹575 | ₹625 |
| .co.in | ₹475 | ₹525 |
| .com | ₹1,150 | ₹1,150 |
Every other extension is on the domain pricing page. For .in and its second-level extensions (.co.in, .net.in, .org.in and others), personal registrant details are not shown in public WHOIS. This is free and automatic; there is nothing to switch on.
Frequently asked questions
What is the domain hierarchy?
It is the tree structure of the Domain Name System. The root is at the top, top-level domains such as .in and .com are below it, registered names such as yourbusiness.in are below those, and subdomains such as www or shop sit under a registered name.
What is the difference between a top-level domain and a second-level domain?
The top-level domain is the last label, such as .in or .com, run by a registry. The second-level domain is the label just before it, such as "yourbusiness" in yourbusiness.in, which you register through a registrar.
Is .co.in a top-level domain?
No. The top-level domain is .in. The .in registry runs .co.in as its own second-level extension, so a name like yourbusiness.co.in is registered and used just like a name directly under a TLD.
Do I need to register a subdomain separately?
No. Once you own a domain, you create subdomains such as shop.yourbusiness.in by adding DNS records, usually through your hosting control panel. There is no registration fee, though a hosting plan may limit how many you can add.
What is the root domain?
The root is the top of the DNS tree, written as a single trailing dot that browsers hide. The root zone lists every top-level domain and its nameservers, and it is where uncached lookups begin.
How long can a domain name be?
Each label between dots can be up to 63 characters, and the full name up to 253 characters. Letters, digits and hyphens are allowed, and a label cannot start or end with a hyphen.
Who manages top-level domains?
IANA maintains the root zone under ICANN's coordination. Each top-level domain is run by its own registry: generic TLDs follow ICANN policy, and country codes such as .in follow their own country's registry, which for .in operates under NIXI.
Ready to claim your place in the tree? Search for a domain, compare extensions on the domain pricing page, or read How do domain names work for the lookup in detail.
Check your name as a .in, .co.in, .com or another extension, and register it with a NIXI-accredited .IN registrar.
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