How to Create a Subdomain in ISPConfig

This guide shows you how to create a subdomain, such as blog.yourdomain.com, for an existing website in the ISPConfig control panel. It is written for Noiz clients managing their own hosting account through ISPConfig. ISPConfig offers two kinds of subdomain: a standard subdomain, which shares the parent website's content or redirects visitors elsewhere, and a vhost subdomain (shown in the panel as Subdomain (Vhost), and sometimes called a vhostsubdomain), which behaves like a small website of its own with its own folder and settings. This article explains the difference and walks you through creating both.

Last reviewed: 27 July 2026, against ISPConfig 3.3.1p1. This guide is written for Noiz hosting and is kept current against ISPConfig, including the field names and limits that changed after the widely circulated 3.1 manual was written. It complements, and does not replace, the official ISPConfig documentation linked below.

Official Documentation Reference

• Subdomains (ISPConfig 3 Documentation): the current official documentation on the different ways to create a subdomain.
• Subdomains in the Sites module (ISPConfig 3 Documentation): the same topic within the official Sites module documentation.
• ISPConfig Documentation overview: the index of all official ISPConfig documentation, including the full manual.

Prerequisites

• You can log in to the ISPConfig control panel.
• An existing website in ISPConfig to attach the subdomain to. If you have not created one yet, follow How to Create a Website in ISPConfig first.
• A hosting plan with an unused subdomain allowance. The Subdomain menu item is hidden entirely when your plan allows no subdomains, and once you have used your allowance up, saving a new one fails with The max. number of web subdomains for your account is reached.
• A DNS record for the subdomain, for example an A or CNAME record for blog.yourdomain.com, pointing at your Noiz hosting server. You can create the subdomain in ISPConfig first and sort out DNS afterwards, but the subdomain only works in a browser once DNS is in place.

Choose the Right Type of Subdomain

Before you open any forms, decide what the subdomain should do. ISPConfig 3.3 gives you up to three options:

• Standard subdomain (the Subdomain menu item): the subdomain is attached to the parent website and, by default, shows exactly the same content as the main domain. You can optionally redirect it to a folder of the site or to another URL. Its whole form is a handful of fields, so it has no web space, PHP settings or SSL configuration of its own. Choose this when the subdomain is simply another name for the existing site, or a signpost pointing somewhere else.
• Vhost subdomain (the Subdomain (Vhost) menu item): the subdomain gets its own document root inside the parent website's folder, plus its own PHP, SSL and other settings, without any redirect rules. Choose this when you want to run separate content or a separate application, for example a WordPress blog at blog.yourdomain.com, alongside the main site. This menu item only appears if the feature is enabled on your server; if you do not see it, use the next option instead.
• A full website on a subdomain: when creating a website, you can enter a subdomain such as shop.yourdomain.com straight into the Domain field. ISPConfig then creates a completely independent website with its own web space, counted against your website allowance rather than your subdomain allowance. See How to Create a Website in ISPConfig.

One caution from the official manual: do not use a standard subdomain redirected to a subdirectory if you plan to install a content management system such as WordPress, Joomla or Drupal in that subdirectory. The redirect is built from rewrite rules, and these usually collide with the CMS's own rewrite rules. For a CMS, use a vhost subdomain or a full website instead. A standard subdomain redirect to a subdirectory is fine for static HTML files.

A related feature you may notice in the same menu is the aliasdomain. The difference is simple: a subdomain uses the same domain name as the parent website, for example blog.yourdomain.com under yourdomain.com, while an aliasdomain points a completely different domain name at the same site.

Create a Standard Subdomain

Open the Subdomain Form

1. Log in to the ISPConfig control panel.
2. Click the Sites module in the top navigation.
3. In the left menu, under Websites, click Subdomain. A list of any existing subdomains on your account appears.
4. Click the Add new Subdomain button.

Complete the Form

Fill in the fields described below, then click Save.

• Host: enter only the subdomain part, without the main domain. For blog.yourdomain.com, enter blog. A wildcard is rejected here with Wildcard subdomains are not allowed; wildcard cover is set on the parent website's Auto-Subdomain field instead, not on an individual subdomain.
• Domain: select the parent website from the drop-down, for example yourdomain.com. The list shows the websites already configured on your account, each entry giving the domain name followed by the server it runs on.
• Redirect Type: leave this set to No redirect if the subdomain should show the same content as the parent website. To redirect instead, choose one of the options; on an Apache server the current interface labels them No flag, R (Temporary redirect), L (Last redirect rule), R,L (Temporary redirect + last rule) and R=301,L (Permanent redirect + last rule). Following the official manual's guidance: for a redirect to another URL choose R,L, or R=301,L if the move is permanent, and for a redirect to a subdirectory of the site choose L. On a server running nginx the Apache flags are hidden and the list offers last, break, redirect, permanent and proxy instead; the manual's advice there is to use permanent for a URL redirect. proxy is the odd one out: it fetches the target's content and serves it under the subdomain's own address rather than sending the visitor away, it accepts only a full URL in Redirect Path, and selecting it adds an extra Options tab to the form holding a Proxy Directives field.
• Redirect Path: the redirect target. For a URL redirect enter the full address ending in a slash, for example https://www.anotherdomain.com/. For a subdirectory redirect enter the path relative to the website's document root, beginning and ending with a slash, for example /blog/. Leave the field empty when Redirect Type is No redirect. Anything else is refused with Invalid redirect path. Valid redirects are for example: /test/ or https://www.domain.tld/test/.
• Don't add to Let's Encrypt certificate: if the parent website uses a Let's Encrypt SSL certificate, ISPConfig automatically includes the new subdomain in that certificate. Tick this box only if the subdomain's DNS does not point at the hosting server, otherwise the failed inclusion can hold up certificate renewal. If you do not see this checkbox, it simply is not applicable to your site.
• Active: leave this ticked so the subdomain is enabled as soon as it is created.

Save and Wait for the Configuration Update

1. Click Save. You return to the subdomain list, where the new entry appears.
2. Watch for the small red change indicator near the top of the panel. It carries a count of the changes still queued and clicking it lists them. ISPConfig's server process collects that queue once a minute, so the web server configuration is normally written within a minute of saving.

Create a Subdomain (Vhost)

The Subdomain (Vhost) menu item only appears in the Sites module when the server administrator has enabled vhost subdomains. If you do not see it on your account and you need a subdomain with its own content, create the subdomain as a full website instead, or open a support ticket.

1. Click the Sites module in the top navigation.
2. In the left menu, under Websites, click Subdomain (Vhost).
3. Click the Add new subdomain button.

The form that opens looks very similar to the website form, because a vhost subdomain really is a small website of its own. Three fields are specific to it:

• Hostname: enter only the subdomain part, without the main domain. For blog.yourdomain.com, enter blog.
• Domain: select the parent website from the drop-down, for example yourdomain.com.
• Web folder: enter the folder, relative to the parent website's web space, that will hold this subdomain's files. For example, blog creates a separate blog folder alongside the parent site's files, while web/blog uses a subdirectory inside the parent site's public web directory. To share the parent website's own document root, enter web. The field must not be empty, and in ISPConfig 3.3.1p1 the value must not start with a slash at all: enter web, not /web or /web/. Older ISPConfig documentation, and the panel's own prompt when you leave the field blank, still suggest the /web/ form; if a value is refused with Invalid folder entered. Please do not enter a slash., drop the leading slash and save again.

The remaining fields, such as Traffic Quota, PHP, SSL, Let's Encrypt SSL, Auto-Subdomain and Active, work exactly as they do for a website; see How to Create a Website in ISPConfig for what each one means. Two things the website form has are deliberately absent here, because the parent website owns them: there is no Harddisk Quota field, since the subdomain's files sit inside the parent's web space and count against the parent's disk allowance, and there is no Backup tab, since the subdomain is covered by the parent website's backup settings. The Server, Client, IPv4-Address and IPv6-Address fields are absent for the same reason. Because a vhost subdomain does have its own SSL configuration, you can tick SSL and Let's Encrypt SSL to give it its own free HTTPS certificate once its DNS record points at the server. Scripts such as PHP run under the parent website's user, so there are no file permission problems between the parent site and the subdomain.

Click Save, then wait for the red change indicator to clear as before. Upload the subdomain's files to the folder you specified in Web folder, using the parent website's FTP access.

Point DNS at the Subdomain and Verify

1. Make sure the subdomain has a DNS record. A CNAME record pointing the subdomain at the main domain, for example blog.yourdomain.com to yourdomain.com, is the simplest option; an A record holding the server's IP address works equally well. The ISPConfig manual is firm on this point: every name attached to a website, including its auto-subdomain and any alias or subdomain, has to be reachable from outside before the site behaves as configured. If Noiz hosts your DNS and you are unsure, open a support ticket and the record can be checked for you.
2. Allow time for the DNS change to spread; this can take up to 24 hours worldwide, though it is usually much faster.
3. Open http://blog.yourdomain.com in a browser. A standard subdomain with No redirect shows the parent website's content; a redirecting subdomain sends you to the target you configured; a vhost subdomain shows whatever you uploaded to its Web folder.

Troubleshooting

• The subdomain shows exactly the same pages as the main site: for a standard subdomain with Redirect Type set to No redirect, this is the designed behaviour, not a fault. If you wanted separate content, create the subdomain as a Subdomain (Vhost) or as a full website instead.
• Saving fails with "There is already a website or sub / aliasdomain with this domain name": the same subdomain already exists somewhere on the system, possibly as a website, an aliasdomain or an auto-subdomain. Check your website list and subdomain list first; if you cannot find it, contact support.
• The subdomain does not load in a browser: wait for the red change indicator in the panel to clear, then check DNS. The subdomain needs its own A or CNAME record; a record for yourdomain.com alone does not cover blog.yourdomain.com unless a wildcard record exists.
• The browser shows a certificate warning on the subdomain: the subdomain is not yet covered by a valid SSL certificate. For a standard subdomain, make sure its DNS points at the server and that Don't add to Let's Encrypt certificate is not ticked, then edit and re-save the parent website so the certificate is reissued. For a vhost subdomain, tick SSL and Let's Encrypt SSL on the subdomain itself once DNS resolves.
• A CMS installed in a redirected subdirectory shows broken links or endless redirects: the subdomain's rewrite rules are colliding with the CMS's own rules. Remove the directory redirect and recreate the subdomain as a Subdomain (Vhost) or a full website, as the official manual recommends.
• The Subdomain (Vhost) menu item is missing: vhost subdomains are not enabled on your server, or your plan does not include them. Create the subdomain as a full website instead, or open a support ticket.

If you get stuck at any point, open a support ticket with the Noiz support team and include the full subdomain name, the parent website it belongs to, which type of subdomain you are creating, and the exact error message or symptom you are seeing.