Many web hosts offer a feature called addon domains. This feature allows you to use more than one domain on a single hosting account, essentially providing hosting for multiple websites. While this may sound like a great idea, it can quickly become a nightmare.
Addon domains are added to your web hosting control panel. They tell the web server where to send traffic from that domain. When someone visits that domain, the web server directs the person to your account. Your account sends them to the directory you’ve created for your addon domain. As far as the visitor knows, the domain they are visiting is being hosted on it’s own account.
Many people use addon domains to avoid paying for additional hosting accounts or a reseller account. It’s easy to see why when your account allows you to freely add additional domains with no additional cost. So where do the problems come in?
Imagine you have ten websites that you would like to host. For our example, we’ll break them down further. In this example, you have:
2 storefronts using Prestashop
4 community forums using phpBB
3 business websites using Drupal
1 marketing blog using WordPress
Each website is running under the same control panel. This makes it easy to access them all because they are in the same general area. However, the hidden problems and dangers will soon creep up.
The Pool is Only So Big
Your web host provides a set allotment of server resources beyond the storage and data transfer rate that you focused on when signing up. You also have a set amount of CPU, RAM, Entry Processes, I/O, and Inode count. This allotment is the same for every account on the server, regardless of how many addon domains are being used.
Each addon domain will pull from this resource pool. While this won’t be a problem for low traffic sites with sufficient optimization, it will become an issue when your viewership increases. As more people view your web sites and the complexity of them is put to the test, the resource pool will soon begin to dwindle away. Soon you will notice speed and loading issues for multiple sites. You new wave of visitors will be meet with slow loading pages and error messages stating “Resource Unavailable” or perhaps database connection error messages.
Addon domains can also present a major threat to all of the web sites on your account. Imagine that one of the web sites on your account has a security hole that has not yet been patched. Perhaps you’re running an outdated plugin or theme which has a vulnerability you are unaware of. This vulnerability can become the doorway to all of your websites.
If a malicious attacker is able to access the filesystem of one of your websites, they will potentially have access to the rest of your web sites. This will allow them to deface and destroy files for every website under your single account, possibly harming the reputation of your web sites in the process. They may also use your account to send spam from, which can get the web server blacklisted by email providers and affect everyone on the server.
To make matters worse, an attacker could use this intrusion to gain access to your database and leak the information within to the world. One hole can lead to a lot of damage and headache for you.
Tons of Clutter
As you add more addon domains, the filesystem can become cluttered. I’ve worked with accounts in which people have hosted 50 addon domains under a single CPanel account. This can be bothersome as it takes longer to find things if they aren’t properly organized. Even when you do have sites neatly placed in various directories, you still have to find what you’re looking for.
Additionally, you have to face another issue known as inode usage. Inodes are a way for the operating system to keep track of files and directories. Each inode represents a single file or directory. Your web host will have a limit on the number of files you can have on your hosting space, even if they say the storage space is unlimited. As you add more web sites to your account, you will naturally be reducing your available inodes. Once you hit your limit your account can no longer accept files, and this includes receiving email.
Addon Domains are NOT for Reselling Hosting
Some people will use the addon domain feature to run a hosting business. This is simply a terrible idea on every level. In the case of CPanel, there is no way to provide CPanel access for your customers without giving them the master account login. If you give them that, they have access to everything, including other web sites you host.
You are also exposing every customer’s web site to the issues above. One malicious attack on a security vulnerability in a customer’s web site can effectively bring an end to the web sites for each customer you have.
In short, don’t try to build a hosting business off of addon domains. It can quickly lead to headaches.
Host Multiple Domains the Correct Way
The best way to host multiple domains is by using a reseller hosting account. A reseller hosting account provides a way to create single hosting accounts which you can use for your additional domains. This means that each domain can have it’s own control panel and allotment of resources. No more sharing CPU and RAM since each domain will have it’s own to pull from.
Using a reseller account will also help prevent malicious attacks from spreading to your other domains. If one web site is defaced, the others won’t be in the same filesystem to be discovered and suffer the same fate. This can save you hours of times since you will only need to repair one site instead of ten.
Hosting multiple websites under a reseller account also makes it easier to move a popular website when it outgrows a shared environment. Since the website will be inside of it’s own control panel account, your web host will have an easier time migrating it to a Managed VPS or Managed Dedicated Server. If it was an addon domain, it would be more difficult to move. In some cases the move would be your responsibility since the host may not offer migration services for addon domains.
Avoiding the Headaches
I understand why some people choose to use the addon domain option. When you’re unable to afford additional hosting accounts or your web host does not offer reseller hosting, using the addon domain feature is your only option. However, keep in mind the issues that can arise. I’ve seen first hand how multiple addon domains can dissolve a shared hosting account’s resources like they were water. I’ve also helped repair the damage done to the web sites of dozens of addon domains when a single web site in the group was hacked.
If you can avoid the headaches, do so. Go with a reseller hosting plan if you need to host multiple domains. If your web host does not offer a reseller plan, find one that does.