Ethereum Name Server

I spent the last day just dabbling in Ethereum claiming the domain name jqphu.eth. To make this blog not entirely a self-help blog and be somewhat technical I though it'd go through what on earth do I mean by "claiming a domain name on the blockchain".

Domain Name System (DNS)

Let's start with traditional domain name servers. To simplify, every connection on the internet has a unique identifier known as an ip address. This can be thought of as your address. If I want to communicate with your through the internet I use your ip adress.

However, when accessing websites we don't use ip addresses as they are cumbersome and hard to remember. Instead, you access websites through a domain name. If I want to talk to google I go to google.com.

❯ ping blog.justinphu.dev
PING jqphu.github.io (185.199.109.153) 56(84) bytes of data.

Here, when I try to access the domain blog.justinphu.dev I get pointed to the ip address 185,199,109.153.

The translation from a domain to an ip address is handled by the Domain Name System (DNS) which can be thought of as a glorified adderssbook. It maps various domains to ip addresses. The benefit provided here is you can point to various ip addresses (changing servers) with the same domain. Clearly, blog.justinphu.dev won't point to a single server / ip address but varies depending on the DNS server you hit.

We can query the nameserver directly:

❯ nslookup blog.justinphu.dev
Server:         192.168.0.1
Address:        192.168.0.1#53

Non-authoritative answer:
blog.justinphu.dev      canonical name = jqphu.github.io.
Name:   jqphu.github.io
Address: 185.199.108.153
Name:   jqphu.github.io
Address: 185.199.109.153
Name:   jqphu.github.io
Address: 185.199.110.153
Name:   jqphu.github.io
Address: 185.199.111.153

The nameserver is 192.168.0.1 which is just my router beucase of networking things. This is unimportant, my router will go to another domain name server and resolve the addresses.

Here, there are many addresses to a single domain as my blog is hosted on many servers (thanks to github!).

Great! The oversimplified version is your address is an ip address and the domain is a human readable way to lookup your address. The lookup process happens through a domain name system.

Ethereum Name Servers (ENS)

I'm not going to go into detail about Ethereum but it essentially a decentralized computer or state machine. You can modify the state machine through a transaction. A transaction can be thought of as a simple piece of code that needs to run. A simple transaction is sending money from one account to another.

On the blockchain you're identified by your account. Your account is simply a 42 hexadecimal address (derived from your public key). This is equivalent to your ip address in the example above. For example, my address is 0x1a8906a0EBB799ED4C0e385d7493D11701700d3a.

As you can tell, using that address to send money is going to be cumbersome. If you make a typo of any sort you've now sent money to the wrong account.

In comes Ethereum Name Servers. They provide the mapping of a domain to an address. The difference with DNS is domain names are stored and hosted by centralized companies (like google) whereas with ENS your data is stored directly in the blockchain. This has the pros of being decentralized and the cons of being expensive to change.

Now comes the question is, who facilitates the lookup? The trick is there are smart contracts (just snippets of code stored directly in the blockchain) that execute to trigger the resolving logic. That is both the code to register and lookup domains and the domains themselves are stored directly on the blockchain. There is no intermediary.

Now the registered name is more than just a mapping from a domain name (jqphu.eth) to an address. It is simply a mapping of a domain name to another transaction which can store additional data. In fact, you can lookup my domain name (https://app.ens.domains/name/jqphu.eth/) and see I have information such as my twitter, email, etc. This can go as far as to linking to a static webpage that itself is hosted on the blockchain but that's for another day.

Why Do I Care?

The reason this is particularly useful is the whole concept of blockchains such that it's decentralized. My information is in complete control by me. As long as the blockchain lives and there are nodes, no-one can take this information down. This doesn't come with downsides such as my data is public, it is expensive to change this information, it is not dynamic, etc.

Conceptually, this can enable pseudo-anonymous personalities to be the unifying source of truth for who you are. You can say "I am X and here are all my links" and be definitive that it is correct and not tampered with.

At the end of the day, the biggest win here is I can now say "I'm on the Ethereum blockchain!".