DNS Registrar

In DNS on ENS we learned how ENS aims to extend the functionality of the DNS. On this page we will explore the implementation of DNSSEC, the DNSRegistrar, and the building blocks for gasless DNSSEC.

DNSSEC

DNSSEC (Domain Name System Security Extensions) is an added layer of security on top of DNS that allows for cryptographic verification of records. It establishes a chain of trust from the root key (which is signed by ICANN) down to each key.

All ENS-enabled DNS names are required to use DNSSEC, and the DNSSECOracle is responsible for verifying the signatures.

Claiming a Name Onchain

Since 2021, it has been possible to import a DNS name and use that as an ENS name. This process involves enabling DNSSEC, setting a specific TXT record, and submitting a proof to the DNSRegistrar smart contract.

Expect your TXT record to look something like this:

TXT @ _ens a=<eth-address>

You can learn more about how to import a DNS name in the DNS section, or see how to programmatically complete these steps.

There is no ENS protocol fee to import a DNS name, but it requires a large amount of gas (up to a few million) to submit the proof onchain. Continue reading to learn how this has been mitigated.

Offchain Verification (Gasless)

EP5.1 introduced a new DNSSECOracle and DNSRegistrar which makes it possible to perform DNSSEC verification at query time, enabling truly free usage of DNS names in ENS. We call this "gasless DNSSEC".

It works by enabling wildcard resolution at the DNS TLD level. During the name resolution process, if a name doesn't already exist onchain but has been configured for usage in ENS, the DNSSEC proof will be fetched offchain via CCIP Read and then verified onchain with the same DNSSECOracle mentioned above.

Import a DNS name gaslessly

To configure a DNS name for usage in ENS, simply add a TXT record with the following format:

TXT @ ENS1 <resolver-address>

The resolver-address implementation is customizable just like any other ENS resolver. To get started quickly, a special ExtendedDNSResolver has been deployed which allows users to specify an ETH address that the name should resolve to within the same TXT record. To use this setup, simply add a record with the following format:

TXT @ ENS1 <extended-resolver-address> <eth-address>
TXT @ ENS1 0x238A8F792dFA6033814B18618aD4100654aeef01 0x225f137127d9067788314bc7fcc1f36746a3c3B5

Other

TLD Ownership

You can lookup the owner of any TLD by calling the Registry.owner(bytes32 node) function. If at least one domain has been imported for this TLD (via the onchain method), the owner will be either the DNSRegistrar or a smart contract controlled by the respective registry operator.

If a TLD has not yet been activated, the owner will return 0x0 and it may require one user to import a name onchain to activate the TLD. See the supported TLD list for more info.

Programming DNSSEC Proofs

To help you interact with DNSSEC data and the DNSRegistrar, we provide a few libraries.

• DNSProvejs = A library for querying and validating DNSSEC data from DNS
• ENSjs = A library for interacting with ENS smart contracts

Retrieving a proof

import { createPublicClient, http } from 'viem'
import { mainnet } from 'viem/chains'
import { addEnsContracts } from '@ensdomains/ensjs'
import { getDnsImportData } from '@ensdomains/ensjs/dns'

const client = createPublicClient({
  chain: addEnsContracts(mainnet),
  transport: http(),
})

const dnsImportData = await getDnsImportData(client, {
  name: 'example.com',
})

Submitting the proof to the DNSRegistrar

import { createPublicClient, createWalletClient, http, custom } from 'viem'
import { mainnet } from 'viem/chains'
import { addEnsContracts } from '@ensdomains/ensjs'
import { getDnsImportData, importDnsName } from '@ensdomains/ensjs/dns'

const mainnetWithEns = addEnsContracts(mainnet)

const client = createPublicClient({
  chain: mainnetWithEns,
  transport: http(),
})

const wallet = createWalletClient({
  chain: mainnetWithEns,
  transport: custom(window.ethereum),
})

const dnsImportData = await getDnsImportData(client, {
  name: 'example.com',
})

await importDnsName(wallet, {
  name: 'example.com',
  dnsImportData,
})

Other functions

// Get the list of suffixes
DNSRegistrar.suffixes
// Get Oracle
DNSRegistrar.oracle

DNSRegistrar.claim(bytes name, bytes proof)
DNSRegistrar.proveAndClaim(bytes name, tuple[] input, bytes proof)
DNSRegistrar.proveAndClaimWithResolver(bytes name, tuple[] input, bytes proof, address resolver, address addr)