A beginner's guide to ENS domains: key things to know

What are ENS domains and how do they work?

The Ethereum Name Service (ENS) is a distributed, open, and extensible naming system based on the Ethereum blockchain. Its primary purpose is to map human-readable names like alice.eth to machine-readable identifiers such as Ethereum addresses, content hashes, and metadata. This eliminates the need to copy and paste long hexadecimal strings, reducing errors and improving user experience across dApps, wallets, and payment systems.

ENS operates as an on-chain registry with a hierarchical structure. The root domain (".eth") is governed by a smart contract, and subdomains can be created by domain owners. Each ENS name is an ERC-721 non-fungible token, meaning you truly own it and can transfer, sell, or use it as collateral. The system uses two core components: the registry, which stores the owner of each domain and its resolver, and the resolver, which translates the name into an address or other records. When you register your .eth now, you mint a token that grants you exclusive control over that name for a set period, typically one to five years.

The technical mechanism is straightforward: when a user sends a transaction to alice.eth, their wallet queries the ENS registry for the resolver contract, then asks that resolver for the corresponding Ethereum address. This process is handled transparently by supporting wallets like MetaMask, Rainbow, or Frame. Currently, over 3.5 million .eth names have been registered, and the system supports dozens of record types including ETH addresses, Bitcoin addresses, IPFS content hashes, and email handles.

Registration and renewal mechanics: term limits, gas costs, and fees

Unlike traditional DNS domains which you purchase outright, ENS names are rented on a time-limited basis. Registration requires a smart contract interaction that costs gas (Ethereum network fees), plus an annual registration fee that varies by name length:

1. 7+ character names: Standard annual fee of approximately $5 in ETH (subject to fluctuation and governance votes)
2. 5-6 character names: Premium pricing, typically $160-$640 per year
3. 4 character names: Lower premium, around $640 per year
4. 3 character names: Highest tier, roughly $1,280 per year

Gas costs for registration depend on network congestion. On a busy day, a single transaction can cost $30-$150 in ETH. Renewals are handled by the same controller smart contract, and you can extend your registration up to 90 days before expiration. If a name expires, it enters a 90-day grace period during which only the previous owner can renew. After that, a 28-day "premium auction" begins where anyone can claim the name by paying the last holder's annual fee plus a declining premium. This mechanism prevents squatting while giving original owners a reasonable window to recover their name.

One often overlooked detail is the royalty on ens. The ENS DAO charges a royalty on ens secondary market sales: a 5% fee is applied to trades on open marketplaces like OpenSea and LooksRare. This royalty funds the ENS treasury, which supports development grants, community initiatives, and protocol upgrades. As an owner, this means you net 95% of the sale price, but the fee is deducted automatically by the marketplace contract.

DNS names imported to ENS: bridging traditional and web3

A powerful but often misunderstood feature is DNS name integration. You can import any DNS domain you already own (like example.com) into ENS and use it as an Ethereum name. This requires setting a DNS TXT record at your domain provider pointing to your Ethereum address, then executing a transaction on Ethereum to verify ownership. Once verified, your DNS name functions identically to a .eth name: it can receive payments, store records, and resolve to addresses.

The process involves three steps:

1. Add a TXT record at your DNS provider with the name _ens.yourdomain.com and value a=0xYourEthereumAddress
2. Call the DNS registrar smart contract with a proof of the TXT record (generated via an oracle like ENS's DNSSEC oracle)
3. Set the resolver to point to your imported domain's records

This feature is particularly useful for businesses that want to accept cryptocurrency without forcing customers to learn .eth naming. However, it carries a tradeoff: you must maintain both the DNS subscription (paid in fiat) and the ENS integration (paid in gas). If your DNS expires, the ENS mapping breaks. Additionally, DNS names imported this way cannot be transferred on-chain; ownership remains tied to the DNS registrar. For full decentralization, native .eth names remain the superior choice.

ENS resolution and reverse resolution: queries and use cases

ENS supports two types of resolution. Forward resolution converts a name to an address — this is what happens when you send ETH to alice.eth. Reverse resolution works in the opposite direction: given an address, find its primary ENS name. This is used by wallets to display "YourName.eth" instead of "0xAbc...Def".

Reverse resolution requires deploying a separate record via the ENS registry. Not all addresses have one, so wallets typically show the first name found in the resolver, or fall back to a hexadecimal display. Developers can query the ENS contract via ethers.js or web3.js with a single function call:

• resolver.addr(name) for forward resolution
• resolver.name(address) for reverse resolution

Practical use cases extend far beyond simple payments. dApps use ENS names for login systems (replacing usernames and passwords), decentralized websites (via IPFS content hashes stored in ENS records), and multi-chain address aggregation. For example, a single ENS name can store your Bitcoin, Litecoin, and Dogecoin addresses simultaneously. The resolver contract supports arbitrary records, enabling complex metadata like avatars, social links, and contact info without centralized servers.

Secondary market, royalties, and tax considerations

ENS domains trade actively on open marketplaces. Short names (3-4 characters) and highly memorable phrases command significant premiums — a three-character .eth like 123.eth sold for 300 ETH in 2022. The secondary market is purely peer-to-peer: you list your domain on OpenSea, LooksRare, or ENS-specific platforms like ENS.vision, and a buyer purchases it. Settlement happens via the ERC-721 contract, and ownership transfers immediately.

As noted earlier, the 5% royalty applies to all secondary sales. This is hardcoded into the ENS token contract and cannot be bypassed. Sellers should factor this into their pricing. For tax purposes, selling an ENS domain is treated as disposing of a capital asset in most jurisdictions. If you held the domain for more than one year, you may qualify for long-term capital gains rates. Short-term holdings (under one year) are taxed as ordinary income. Additionally, gas fees paid for registration and transfers are considered cost basis adjustments, not deductible expenses — consult a tax professional for your specific situation.

One important caveat: ENS domains are not "domains" in the internet infrastructure sense. They do not give you a website URL by default. To host a decentralized site, you must set an IPFS content hash, which requires uploading your site to IPFS and updating the resolver record. This process is separate from the domain registration itself and incurs additional gas costs. Many beginners confuse ENS with traditional DNS, expecting automatic web hosting — the two systems serve different purposes.

Security and key management: protecting your .eth name

Since your ENS name is an NFT, its security depends entirely on the security of the wallet holding it. Here are essential practices:

• Hardware wallet: Always store valuable ENS names on a Ledger or Trezor device, never on a hot wallet
• Revoke approvals: After listing or using your ENS in a dApp, revoke token approvals via Etherscan or Revoke.cash to prevent malicious contracts from draining your assets
• Multi-signature custody: For high-value names (3-4 characters), consider using a Gnosis Safe multi-sig wallet with multiple signers across different devices
• Set reverse record carefully: Your reverse ENS record points to your primary name; if you change it, dApps will display the new name. Never set a reverse record for a name you do not control, as phishing attacks can use this to impersonate you

Phishing attacks targeting ENS owners are increasingly common. Scammers send fake renewal emails, create fake dApps that request your seed phrase, or impersonate marketplaces. Legitimate ENS renewals only happen through the official ENS app (app.ens.domains). Never enter your private key or seed phrase into any third-party site. The ENS DAO maintains a list of verified dApps on the official ENS website.

For beginners, the steepest learning curve is understanding gas costs and timing. Registration is cheapest during low-activity periods — typically weekends at 0:00-6:00 UTC. Use gas trackers like Etherscan Gas Tracker or ETH Gas Station to estimate optimal fees. Some wallets allow you to set a custom gas limit; for ENS operations, the default limit (usually 150,000-200,000) is sufficient, but complex operations with multiple records may require 300,000 or more. Overestimating gas costs you the difference if the transaction uses less; underestimating causes the transaction to fail, wasting the gas entirely.

As the ecosystem matures, ENS continues to expand with multi-chain support (Polygon, Arbitrum, Optimism), layer-2 name systems (ENS on L2 via NameWrapper), and integration with traditional finance. Whether you are a developer building a dApp, an investor looking for short-name opportunities, or a casual user wanting a readable wallet address, understanding these fundamentals will help you navigate the space confidently. Start by registering a short, memorable name that reflects your brand or identity — and always remember that ownership means responsibility for gas costs, renewals, and security.