A Comprehensive Guide to Ethereum Name Service (ENS)

Introduction to ENS

Ethereum Name Service (ENS) is a distributed, open, and extensible naming system built on the Ethereum blockchain. It translates human-readable domain names (e.g., alice.eth) into machine-readable identifiers like:

• Ethereum addresses
• Content hashes
• Metadata

ENS also supports reverse resolution, enabling the association of metadata (e.g., canonical names or interface descriptions) with Ethereum addresses.

How ENS Compares to DNS

While ENS shares DNS’s hierarchical structure (domains separated by dots), its architecture diverges due to Ethereum’s blockchain capabilities:

• Top-level domains (e.g., .eth) are owned by smart contracts called registrars, which govern subdomain allocation.
• Any user can claim a domain by following registrar rules.

Example: Alice owns alice.eth → Can create subdomains like pay.alice.eth.

👉 Explore ENS domains today

ENS Architecture: Core Components

1. ENS Registry

A smart contract that tracks domains and stores:

• Owner of the domain
• Resolver responsible for the domain
• Time-to-Live (TTL) for cached records

Owners (users or contracts) can:

• Set resolvers/TTL
• Transfer ownership
• Modify subdomains

2. Resolvers

Smart contracts that convert domain names into addresses. Key features:

• Supports multiple record types (addresses, hashes, etc.).
• New record types can be added via EIP standards without altering the registry.

Resolution Process:

1. Query the registry for the domain’s resolver.
2. Ask the resolver for the target address.

Namehash: How ENS Handles Domains

ENS uses cryptographic hashes (256-bit) for efficiency:

• Namehash algorithm generates unique hashes while preserving hierarchy (e.g., alice.eth → 0x787...).
• Domains are normalized via UTS-46 standard (case-insensitive, invalid-character filtering).

👉 Learn more about Namehash

Getting Started with ENS

For DApp Developers

1. Enable ENS in your DApp
2. Choose from available ENS libraries.

For Smart Contract Developers

1. Resolve names on-chain
2. Write custom resolvers or registrars.

API References

• ENS Registry
• Public Resolver
• Test Registrar

FAQ

1. What’s the cost of registering a .eth domain?

Prices vary based on domain length (e.g., 3+ characters). Annual renewal fees apply.

2. Can I transfer my ENS domain?

Yes! Owners can transfer domains to other addresses via the ENS Manager.

3. How does reverse resolution work?

It links Ethereum addresses to metadata (e.g., 0x123... → alice.eth).

4. Is ENS compatible with wallets like MetaMask?

Absolutely. Most Ethereum wallets support ENS domain inputs.

5. Where can I manage my ENS domains?

Use the ENS Manager or official ENS apps.

Documentation translated by Liubenben. Original version: ENS Docs. Last updated: 10/31/2019.

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