What Is An ENS Subdomain And What Is It Used For?

As we navigate through the wild world of Web3, we are continuously discovering new uses for even the most popular services. One example comes from the Ethereum Name Service (ENS). By now you have probably heard of ENS domains, but have you heard of ENS subdomains?

An ENS subdomain is a third-level (3LD) domain that precedes both the second-level domain (2LD) and the top-level domain (TLD). ENS uses the same syntax as DNS (a dot separated right-to-left). For example, alex.137pm.eth is 3LD.2LD.TLD. Currently, if you own a 2LD you can create as many subdomains as you want.

In this article, you will learn exactly what an ENS subdomain is, some current issues regarding it, as well as its potential use cases.

The information in this article was gathered from this tweet, found below.

If you don’t already know what an ENS domain is, be sure to read our in-depth guide that walks you through what it is, how to get one, and some additional benefits of owning one.

Before understanding what an ENS subdomain is, it’s important to note the other parts of an ENS domain. Currently, there are three parts to an ENS domain including the subdomain:

• Top-Level Domain (TLD) .eth - This is owned by the smart contract.
• Second-level domain (2LD) - This is what you own.
• Third-level domain aka Subdomain (3DL) - Another layer of the 2LD that you own.

Before you can create your own subdomain, you need to get your own second-level domain. However, if someone has their own 2LD, they can easily send you your own subdomain.

The cost to purchase a second-level domain (2LD) is as follows:

• 5+ character .eth names: $5 in ETH per year. 
• 4 character .eth names: $160 in ETH per year. 
• 3 character .eth names $640 in ETH per year.

This means that most 2LD names are registered for an average cost of only $5.00 per year. That being said, there is no ongoing cost for creating an ENS subdomain (3LD). 

So, if you own a subdomain (such as 137pm.eth) you can create as many subdomains (like alex.137pm.eth), as you want. As of now, the only cost is the initial gas fee to register the subdomain.

So as long as you own a 2LD, you can create an unlimited number of subdomains and own it forever, with no extra steps.

Of course, there are a couple of main issues holding back mass adoption of ENS subdomains.

1. 2LD owners can take away a subdomain anytime unless they totally give up control of their 2LD.
2. Even a one-time gas fee for a subdomain can cost too much money.

But don’t worry, there are solutions currently in the works for both of these issues.

ENS is currently working on a new subdomain registrar contract that will enable 2LD owners to create and distribute subdomains that are locked from the control of the 2LD owner, without the owner having to give up control of their 2LD. 

For example, 137pm.eth could give me control of alex.137pm.eth, without having to give up control of their 2LD (137pm.eth). 

As far as solving the gas fee cost to register a subdomain, ENS is working on a system that allows users to put subdomains and records on layer-2 solutions of their choice. Layer-2 solutions are known to significantly reduce gas fees. Popular examples of Ethereum layer-2 solutions include Immutable X, Polygon, and Polkadot.

You can view a prototype of this system in this article.

The most exciting aspect of ENS subdomains is their potential use cases in the near future. With layer-2s making the cost to create an ENS subdomain very inexpensive, the opportunities are abundant. 

Perhaps wallets will start issuing ENS subdomains, e.g. [user’s name].[wallet provider].eth (alex.metamask.eth). This is comparable to a Gmail account in today's world—which wallet provider will become the Gmail account of ENS names? Only time will tell.

Whether you want to onboard your entire family into the Web3 space or if your family name is just that important to you, perhaps you’d like to create it as a username on the blockchain. So rather than trying to get [your brother’s name].eth, get [your family’s last name].eth & give everyone a subdomain [first name].[last name].eth 

Not only is this the cheaper option, but you can also recover names if anyone in your family loses their wallet.

Another cool use case is the potential for NFT projects and DAOs to give their consumers, partners, and contributors subdomains of their project.eth name. Wouldn’t it be cool if all original VeeFriends minters received their own subdomain like alex.veefriends.eth? This is basically the modern-day equivalent of wearing a badge of honor.

If you’re heavy in the Web3 space then you likely have numerous types of assets and accounts that you have to keep track of. Between your NFTs, cryptocurrency, and multi-sig wallet, you’ve got your hands full. 

Now with ENS subdomains, you can easily organize all of your accounts under your 2LD:

• nfts.alex.eth
• crypto.alex.eth
• multisig.alex.eth

Plus any other type of account you might want to keep track of—set as a reverse record for Ethereum accounts for those purposes.

It’s important to note that, besides being longer, .eth subdomains function exactly the same as .eth 2LDs. You can store any record, receive any crypto, operate a decentralized website, and use it as your Web3 username. The only real advantage of a 2LD is length (and in some cases control).

Furthermore, ENS isn’t just .eth names. It also allows importing DNS names you already own for those. Except, you can’t completely give up control of a DNS name on ENS since ownership follows DNS. With .eth names, you can, since they’re ENS-native.

Ultimately, ENS subdomains are a simple way to create additional domains under your preferred second-level domain. This provides new opportunities for both creators and consumers and is likely what most people will have in the future. To learn more about ENS, check out their website.