DNSLink leverages the powerful distributed architecture of DNS for a variety of systems that require internet scale mutable names or pointers.
Try it out
How does it work?
A DNSLink record is a specifically formatted
TXT record that allows you to link resources to that domain. It follows RFC 1464, which defines a structured format of TXT records as
When you register a domain at your name registrar you can set
TXT records additionally to
Using just a DNS client, anyone can quickly resolve DNSLink, discover available records, and request the resource through linked protocols.
Here is an example for a valid DNSLink record pointing at content root on IPFS:
Looking up DNSLink records
You can use any DNS resolution tool, such as
dig, to lookup
TXT records for a domain.
> dig +short TXT _dnslink.en.wikipedia-on-ipfs.org "dnslink=/ipfs/bafybeiaysi4s6lnjev27ln5icwm6tueaw2vdykrtjkwiphwekaywqhcjze"
MS Windows user?
dig.exeis part of the ISC's
Generic DNS tool like
digwill show all
TXTrecords for a domain. To make things easier, you can use the
> dnslink en.wikipedia-on-ipfs.org /ipfs/QmaCveU7uyVKUSczmiCc85N7jtdZuBoKMrmcHbnnP26DCx
DNSLink records are of the form:
- The prefix
dnslink=signals that the
TXTrecord in question is a DNSLink. This is important as
TXTrecords are used for many purposes that DNSLink should not interfere with.
- Starting with
/<namespace>/ensures multiple links can coexist.
- This prefix allows clients to ignore records linking to unsupported protocols or addressing systems.
- Implementations should never error on invalid record. Simply ignore and move to the next one.
- The remainder after the second
identifierspecific to the
DNSLink Record Example
In the example below, the
identifier is the IPFS CID
DNSLink records MUST be specified on the
_dnslink subdomain instead of defining them directly on the domain:
> dig +short TXT _dnslink.example.com dnslink=/ipfs/bafy...abcd
This allows for secure DNSLink management and
DNSLink implementations automatically lookup the
_dnslink subdomain behind the scenes:
> dnslink example.com /ipfs/bafy...abcd
TXT records per domain
Therefore you are free to specify more than one
dnslink=/<namespace>/<identifier> TXT record per domain:
> dig +short TXT _dnslink.example.com "dnslink=/ipfs/.." "dnslink=/hyper/.." "dnslink=/foo/.."
Multiple values per namespace
Publishing more than one record for the same namespace is allowed by DNS clients and DNSLink libs and this specification, but system responsible for processing those records is free to reject such state as invalid, if it makes no sense for a specific namespace.
DNS specification states that TXT records do not need to arrive at the client in order. It is suggested to sort DNSLink records in lexicographical order before they get evaluated. This ensures deterministic results when more than one record is present,
Redirects and delegation
CNAME is the suggested way for delegating DNSLink resolution from one DNS name to another.
Example below delegates DNSLink record resolution for
example.com to TXT records at
> dig +noall +answer TXT _dnslink.example.com _dnslink.dnslink.dev. 1612 IN CNAME _dnslink.external-service.example.net _dnslink.external-service.example.net. 112 IN TXT "dnslink=/ipfs/bafkqae2xmvwgg33nmuqhi3zajfiemuzahiwss"
Standard DNS chaining rules apply, as noted in RFC 1034:
Of course, by the robustness principle, domain software should not fail when presented with CNAME chains or loops; CNAME chains should be followed and CNAME loops signalled as an error.
TTL of the
TTL for DNS records is usually
3600, which is 1 hour. We recommend setting a low
TTL in the
TXT record, something like
60 seconds or so. This makes it so you can update your name quickly, and use it for website deploys.
Prefer learning by doing? Follow the below tutorial.
It covers DNSLink creation and resolution using popular command-line tools.
Step 0: Find something to link to
And even download it with Kubo
ipfs get /ipfs/Qmc2o4ZNtbinEmRF9UGouBYTuiHbtCSShMFRbBY5ZiZDmU
Step 1: Choose a domain name to link from
For this tutorial, I'll use the domain name
libp2p.io. You can use whatever domain you control. I happen to be using an
ALIAS record on this domain as well (to make the website load directly via the IPFS gateway), but that is not a problem: the convention to prefix the TXT record domain with
_dnslink. allows for complex DNS setups like this.
So the full domain name I'll set the record on is:
Step 2: Set the DNSLink value on a
Let's set the link by creating a
TXT record on the domain name. This is going to be specific to your DNS tooling. Unfortunately there is no standard cli tool or web service to set domain names 🙁.
Every registrar and name server has its own web app, and API tooling. Refer to their respective documentations and tutorials.
The gist is to create a new
TXT record on
_dnslink.libp2p.io with the value:
To illustrate, setting the record via an imaginary DNS CLI tool could look like this:
> my-dns-tool set \ --type=TXT \ --ttl=60 \ --domain=libp2p.io \ --name=_dnslink \ --value="dnslink=/ipfs/Qmc2o4ZNtbinEmRF9UGouBYTuiHbtCSShMFRbBY5ZiZDmU" _dnslink.libp2p.io TXT 60 dnslink=/ipfs/Qmc2o4ZNtbinEmRF9UGouBYTuiHbtCSShMFRbBY5ZiZDmU
Setting it via web interface could look similar to this one:
Step 3: Resolve the DNSLink
Now, let's try resolving the link, and reading the data behind it using namespace/protocol-specific tool.
You can get the link value manually using
dig or another DNS lookup tool:
> dig +short TXT _dnslink.libp2p.io dnslink=/ipfs/Qmc2o4ZNtbinEmRF9UGouBYTuiHbtCSShMFRbBY5ZiZDmU
Extract the value with
> dig +short TXT _dnslink.libp2p.io | sed -E 's/"dnslink=(.*)"/\1/g' /ipfs/Qmc2o4ZNtbinEmRF9UGouBYTuiHbtCSShMFRbBY5ZiZDmU
Then, you can feed the output of that to software that understands IPFS paths.
> ipfs ls /ipfs/Qmc2o4ZNtbinEmRF9UGouBYTuiHbtCSShMFRbBY5ZiZDmU QmeotoX2bE7fVgMvUS9ZXL2RMoZQHiuQVZZR1Hts3JVmUT 265 _previous-versions QmP5JpytsFEQ5Y8oQ875kPrdA1dAtyXAH6U8eKbTUbptNd - bundles/ QmcRUrMyFePBNnvoqZB5Uk7y6aoWGoUW6EB8JWUxztKTma - categories/ QmeVM9YZStiFcjjQYpzJ1KWJsaFGcRWaeMAymSfLydu9mh - css/ QmRJjyE1Bi64AD7MSpt4xKHaiWXq7WGAne8KTzn7UyYeWq - fonts/ Qma6Eg1JMAPjBg827ywDG1nx4TBwxYWxQxeb1CXUkDnrHk - img/ QmdB9xXJHNXnaiikCXVpomHriNGXwvSUqdkC1krtFq4WWW - implementations/ QmXCq4KMZC4mdxovpnrHU9K92LVBLSExLEsrvwTGNEswnv 62880 index.html QmQNjTorGWRTqEwctqmdBfuBBRTj8vQD3iGjNNCu7vA5i9 3138 index.xml QmPsosZeKZTUcBkcucPtPnk3fF4ia4vBdJ6str9CRr6VTQ - js/ QmYBUY8Y8uXEAPJSvMTdpfGoL8bujNo4RKoxkCnnKXoTD9 - media/ QmUZ23DEtL3aUFaLgCEQv5yEDigGP2ajioXPVZZ6S7DYVa 561 sitemap.xml QmRgig5gnP8XJ16PWJW8qdjvayY7kQHaJTPfYWPSe2BAyN - tags/
Or chain it all together:
> dig +short TXT _dnslink.libp2p.io | sed -E 's/"dnslink=(.*)"/\1/g' | ipfs ls QmeotoX2bE7fVgMvUS9ZXL2RMoZQHiuQVZZR1Hts3JVmUT 265 _previous-versions QmP5JpytsFEQ5Y8oQ875kPrdA1dAtyXAH6U8eKbTUbptNd - bundles/ QmcRUrMyFePBNnvoqZB5Uk7y6aoWGoUW6EB8JWUxztKTma - categories/ QmeVM9YZStiFcjjQYpzJ1KWJsaFGcRWaeMAymSfLydu9mh - css/ QmRJjyE1Bi64AD7MSpt4xKHaiWXq7WGAne8KTzn7UyYeWq - fonts/ Qma6Eg1JMAPjBg827ywDG1nx4TBwxYWxQxeb1CXUkDnrHk - img/ QmdB9xXJHNXnaiikCXVpomHriNGXwvSUqdkC1krtFq4WWW - implementations/ QmXCq4KMZC4mdxovpnrHU9K92LVBLSExLEsrvwTGNEswnv 62880 index.html QmQNjTorGWRTqEwctqmdBfuBBRTj8vQD3iGjNNCu7vA5i9 3138 index.xml QmPsosZeKZTUcBkcucPtPnk3fF4ia4vBdJ6str9CRr6VTQ - js/ QmYBUY8Y8uXEAPJSvMTdpfGoL8bujNo4RKoxkCnnKXoTD9 - media/ QmUZ23DEtL3aUFaLgCEQv5yEDigGP2ajioXPVZZ6S7DYVa 561 sitemap.xml QmRgig5gnP8XJ16PWJW8qdjvayY7kQHaJTPfYWPSe2BAyN - tags/
Kubo IPFS CLI has DNSLink resolution built in though, so you could just do the following to achieve the same result as in the tutorial above:
> ipfs resolve /ipns/libp2p.io /ipfs/Qmc2o4ZNtbinEmRF9UGouBYTuiHbtCSShMFRbBY5ZiZDmU
Below are some examples of DNSLink being used in real world.
Robust Website Hosting
It is a good idea to publish DNSLink records with identifiers of website content addressed with non-HTTP protocols (e.g., IPFS). This improves resiliency, and enables user agents to opportunistically upgrade to more modern and decentralized transports and routing protocols.
- IPFS Gateways support resolving DNSLinks automatically. See public gateway list.
- The IPFS Companion browser extension works with Chromium and Firefox. It can resolve DNSLinks automatically and load the content with help of a local IPFS gateway. It will also recover from HTTP server being down, and load content over IPFS, even when redirect is disabled by default. See more in the IPFS Companion documentation.
- Brave browser supports resolving IPFS DNSLinks in form of
ipns://en.wikipedia-on-ipfs.org, it will also detect when website has DNSLink and suggest opening it via supported protocols such as IPFS.
Many websites use DNSLink and IPFS. Some examples:
- https://ipfs.kiwix.org (https://github.com/ipfs/distributed-wikipedia-mirror)
In IPFS Ecosystem
Many IPFS implementations (e.g., Kubo) come with built-in supports resolving DNSLink names on
> ipfs resolve /ipns/libp2p.io /ipfs/Qmc2o4ZNtbinEmRF9UGouBYTuiHbtCSShMFRbBY5ZiZDmU
You can find out more at the IPFS DNSLink documentation.
IPFS gateways resolve DNSLink automatically for:
- Requests for
/ipns/example.comcontent paths. Check it out at https://ipfs.io/ipns/libp2p.io or https://dweb.link/ipns/libp2p.io (the latter will provide proper origin isolation for use in browsers).
- Requests with
Host: example.comHTTP header that includes domain with a valid DNSLink. For example, https://en.wikipedia-on-ipfs.org is backed by an IPFS gateway.
How does that work?
The gateway takes the part after
/ipns/, if it is a DNS domain name, it checks for a DNSLink at either the domain name, or
_dnslink. prefixed version. In this case it finds our DNSLink at
_dnslink.libp2p.io and resolves that.
But what about
libp2p also works, that uses a combination of DNSLink, a
ALIAS record in
libp2p.io, and the IPFS gateway reading domain from the
Host header sent with HTTP request.
The browser first checks for
libp2p.io. DNS finds an
gateway-int.ipfs.io, and those
> dig A libp2p.io gateway.ipfs.io. 119 IN A 126.96.36.199
The browser then connects to HTTP server at
188.8.131.52, using a
Host: libp2p.ioHTTP header.
The IPFS gateway reads the
HOST: libp2p.ioheader, and -- recognizing a DNS name -- checks for an associated DNSLink at either
> dig +short TXT _dnslink.libp2p.io "dnslink=/ipfs/Qmc2o4ZNtbinEmRF9UGouBYTuiHbtCSShMFRbBY5ZiZDmU"
The gateway finds the link at
The gateway fetches the IPFS web content at
/ipfs/Qmc2o4ZNtbinEmRF9UGouBYTuiHbtCSShMFRbBY5ZiZDmUand serves it to the browser.
The browser renders it happily, preserving the original pretty name of
Similar to the IPFS Gateway, IPFS Companion browser extension uses DNSLink natively within the browser to resolve IPFS web content. IPFS Companion has a feature that tests domain names for the presence of dnslink
TXT records, and if it finds them, then it serves content via a local IPFS gateway instead.
You can find out more about how it works at IPFS Companion's DNSLink documentation.
DNSLink protocol is simple enough to use standard DNS libraries, however, more advanced tooling for testing and debugging exists.
There are currently reference implementations for two programming languages available:
Both are tested using the universal DNSLink test harness.
- IPFS and DNSLink
- IPFS Companion and DNSLink
- DNSLink support in Brave browser
- DNSLink support at Cloudflare
- DNSLink support at Fleek
- Youtube: Explanation of how DNSLink and the IPFS Gateway works
Is there an IETF RFC spec?
Not yet. We should write one.
Can I use DNSLink in non-DNS systems?
Yes absolutely. For example, you can use DNSLink to resolve names from alternative systems such as Ethereum Name System (ENS). An example of such "DNS Gateway" can be found at https://github.com/wealdtech/coredns-ens/.
If you use DNSLink for something cool like this, be sure to add it to the Usage Examples section of this doc.
_dnslink.domain instead of
_dnslink.domain does not conflict with
ALIAS records, and is better for operations security: enables you to set up an automated publishing or delegate control over your DNSLink records to a third party without giving away full control over the original DNS zone.
TXT record on
domain is deprecated and resolved by some software only for legacy reasons: we historically started with supporting records on the normal domain, and only found the issue with
ALIAS records later on. Those problems are absent when
_dnslink.domain is used.
Rule of thumb: always use
Why use the
dnslink= prefix in the
dnslink= is there to signal that this
TXT record value is a DNSLink. This is important because many systems use TXT records, and there is a convention of storing multiple space separated values in a single
TXT record. Following this format allows your DNSLink resolver to parse through whatever is in the
TXT record and use the first record prefixed with
Why not use other DNS record types, like
Special purpose records enforce some structure to their values, and these are not flexible enough. We wanted a simple protocol that allowed us to link to any other system or service, in perpetuity. This can only be achieved with systems designed to allow structure within the input. The
TXT record is a good example of this -- it imposes a string value, but it allows the user to make sense out of anything within that string. Sets of users can imposese different rules for resolution.
In our case, this is handled through Multiaddr.
Why not just extend DNS with more record types?
It seems that what DNSLink does could be accomplished by a verity of new special purpose record types. But extending DNS is a very expensive process -- in terms of time and adoption. We wanted to find a way to use all the existing infrastructure without requiring any changes at all.
The Domain Name System (DNS) is a hierarchical and decentralized naming system for computers, services, or other resources connected to the Internet or a private network. ... By providing a worldwide, distributed directory service, the Domain Name System has been an essential component of the functionality of the Internet since 1985.
- somewhat decentralized - it delegates naming authority to nations and organizations world-wide
- hierarchical - it achieves scalable naming via name space partitioning
- scalable - it is the dominant name system on the planet -- most internet traffic uses it
- ubiquitous - as the dominant internet name system since 1985, DNS is well-known and well-supported.
As a name system, DNS has pragmatic solutions for:
- control of names
- scalable naming
- scalable reads and writes
- partition tolerance
- and more
Of course, DNS has shortcomings:
- somewhat centralized - central authorities manage DNS roots (ICANN, etc.)
- censorable - DNS is easy to censor, at the registrar and ISP levels
- temporary - DNS names are rented, not really owned, and can be revoked and seized
- not offline-first - DNS does not have good solutions for values to spread through intermittently connected networks
- cumbersome - buying, registering, and setting values on a name is more complicated than acquiring a mutable pointer should be.
- not program friendly - registering DNS names requires being a human or a human organization with human agents, with access to credit cards. this isn't suitable for lots of programs.
These are all good reasons to develop new, better name systems. But until those work better than DNS, you'll probably use DNS.
See resources at dnslink-std/community.
Developed with the support of Protocol Labs