Domains On The Account
Addon domains: one account, several document roots
Two sites on one plan is efficient right up to the afternoon one of them consumes the account's process limit.
The short answer
An addon domain is a second, independent website inside the same hosting account: its own domain name, its own document root, its own database and its own certificate — drawing on the account's single pool of CPU, memory and processes.
To a visitor the sites are unrelated. To the server they are one tenant, which means they share resource limits, an IP address, a PHP configuration surface and, critically, a fate: one suspension or one compromise applies to all of them.
How many you can add depends on the tier: 1 site on Sprint, 25 on Turbo, 100 on Nitro, and 100 or 500 addon domains on the Overdrive and Redline business plans.
By the HostingFast team · Reviewed 15 August 2026
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Mechanically, adding one creates a directory under the account, points a virtual host at it and adds the DNS records. From that moment the second site is a normal site in every respect except ownership of resources, which it does not have — it borrows from the same allowance as everything else on the account.
That borrowing is the whole story. Two brochure sites will never notice each other. A brochure site sharing an account with a busy store will notice a great deal, because uncacheable checkout traffic consumes the process ceiling that both of them are drawing on.
What the sites genuinely share
One CPU and memory allowance, one entry-process limit, one inode count, one disk quota, one IP address and one account-level suspension status. They can, however, run different PHP releases: MultiPHP Manager sets the version per site, so a legacy application and a current one coexist without argument.
They also share a security boundary. A vulnerable plugin on the least important site sits in the same account as the important one, and cleanup after a compromise is an account-level job rather than a site-level one.
Watch the process limit, not the disk
The failure people actually meet is not running out of space; it is one site's traffic exhausting the shared entry-process ceiling and producing errors on the other. Cached pages barely register, so the risk lives entirely in uncacheable traffic: carts, logged-in areas, search and anything hitting the database on every request.
Check the account's resource graphs weekly and note the hour of the peak. If two sites peak together and the ceiling is being touched, split them before either one has a bad day in public.
When to use a separate account instead
Client sites, always. A paying customer's site should be a separate account so it can be limited, backed up, suspended and handed over independently — and so a problem with one client never touches another. That separation is exactly what the reseller model exists to provide.
Also separate anything with a materially different risk profile or traffic shape: a busy store next to a brochure site, or an experimental project next to the site that pays the bills.
How they work here
Each addon domain gets its own document root, its own mailboxes and its own free SSL certificate, issued and renewed automatically once the name resolves to us. PHP release and extensions are set per site, and daily backups cover the whole account with self-service restores from the panel.
The site allowance is the number to check before ordering: 1 on Sprint, 25 on Turbo, 100 on Nitro. Read Subdomain, Parked Domain and Reseller Hosting next.
Separate sites, one set of limits
The efficient part of an addon domain is obvious and the expensive part is not. This entry sets out precisely what the sites share, which shared thing fails first, and the point at which a separate account is the cheaper answer.
Every addon domain gets its own free SSL certificate, issued and renewed automatically once the name points here.
- Its own docroot, database and certificate
- One process limit between them all
- Per-site PHP releases still available
- Client sites belong in separate accounts
Why HostingFast
Standard on every plan
Site allowances stated per tier
1 on Sprint, 25 on Turbo, 100 on Nitro, and up to 500 addon domains on the Redline business plan.
Free SSL for every addon domain
Each name gets its own certificate, issued once it resolves here and renewed ahead of expiry.
Per-site PHP releases
A legacy application and a current one can share an account without either dictating the other's PHP version.
Mailboxes on each domain
Every addon domain can carry its own mailboxes on its own name, included in the plan.
Resource graphs per account
See the combined CPU, memory and process use, which is the only way to spot two sites peaking together.
Backups covering the whole account
Daily backups take in every site on the account, with restores you run yourself from the panel.
Quick Start
From order to online
- 1
Check the site allowance first
Sprint carries one site. Adding a second means Turbo or above, so confirm the tier before promising anyone a launch date.
- 2
Set the PHP release per site
MultiPHP Manager, per document root. Do not let the newest site drag an older application onto a branch it cannot run.
- 3
Watch the combined peak
Read the resource graphs weekly. Two sites peaking in the same hour against one process ceiling is the failure worth pre-empting.
Built In
Loaded onto every plan
- 1 site on Sprint, 25 on Turbo, 100 on Nitro
- 100 addon domains on Overdrive, 500 on Redline
- A separate document root for every addon domain
- Free SSL issued and renewed for each name
- Mailboxes on every domain you add
- Per-site PHP 8.x version and extension control
- Resource usage graphs at account level
- Daily backups that take in every site the account carries
- Softaculous available for each document root
- In-place upgrades when you outgrow the site allowance
Frequently Asked
What people ask us most often
Can visitors tell a site is an addon domain?
No. It has its own domain, its own certificate and its own content, and the arrangement exists purely inside the hosting account. The only externally visible clue is a shared IP address, which is unremarkable and true of most shared hosting anyway.
What actually fails first when two sites share an account?
The entry-process limit, almost always, and almost always during uncacheable traffic. Cached pages cost the account very little; carts, logins and search hit PHP and the database on every request. If both sites peak in the same hour, that ceiling is where the errors come from.
Can each addon domain run a different PHP version?
Yes. MultiPHP Manager sets the release per document root, so a legacy application can stay on the branch its plugins expect while a newer site runs the current one. Extensions and php.ini values are set per site on the same screen.
Why are addon domains wrong for client sites?
Because trouble travels sideways and ownership gets tangled. One compromise or one suspension applies to every site on the account, and when a client leaves, their site has to be extracted from your hosting rather than handed over. Separate reseller accounts solve both problems at once.
Keep reading
Reseller Hosting
Wholesale accounts, isolated per client, which is where a site with a paying owner belongs.
Parked Domain
The other kind of extra name: registered, pointed here, and serving nothing of its own.
How to Add an Addon Domain
Adding an addon domain step by step, with the document root decision explained before you make it.
VPS Hosting
KVM virtual servers with root access, DDoS filtering and one flat monthly price.
Plesk Hosting
Shared hosting on Plesk, for anyone who would rather group the panel by site than by tool.
Changing hosts? Run through our checklist first.
A straightforward sequence for a switch your visitors never feel: which files move first, how to shift email across without losing a single message, the right moment to repoint DNS, and the two mistakes behind almost all the downtime we get asked to rescue.
Room for the second site.
Twenty-five sites on Turbo or 100 on Nitro, each with its own document root, certificate and PHP release.
View VPS Hosting plans