Wildcard Hostnames

Included with Dynamic DNS Pro and Elite.

1. What This Feature Does

A wildcard hostname answers for every name under one of your hostnames. Create a wildcard for home.example.com and app.home.example.com, test.home.example.com and a.b.home.example.com all resolve to the same address, without adding each one.

The wildcard appears in your list as a hostname of its own, *.home.example.com, with its own address.

2. When You Should Use It

• You run several services on one machine and tell them apart by name (a reverse proxy in front of several web apps, for example).
• Names are created on the fly — test environments, or one name per user — and all go to the same server.

3. When You Should Not Use It

• Different names need different addresses. Add those names as hostnames of their own; a hostname with its own record is not covered by the wildcard.
• You are on the Free plan. Wildcards start at Pro.
• You want to forward the wildcard to a web address. Web Forwarding answers for exact hostnames only.

4. Prerequisites

• Dynamic DNS Pro or Elite.
• The base hostname (for example home.example.com) already in Dynamic DNS, on your own account, with an address set.
• From the dashboard: an A (IPv4) base hostname. For an AAAA hostname, use the API (see below).

5. How It Works (Brief)

• Creating the wildcard adds the hostname *.<base hostname> with a copy of the base hostname's address at that moment, and the 60-second TTL of Pro and Elite.
• A lookup for a name under the base hostname gets the wildcard's address, unless that name exists as a hostname of its own. The base hostname keeps its own address.
• From then on the wildcard and the base hostname are separate. Changing the base hostname's address — from the dashboard or a router — does not change the wildcard's.

6. How to Use It

Create a wildcard

1. In Dynamic DNS, find the base hostname and click Create Wildcard (sparkle icon).
2. The Create Wildcard DNS dialog shows the Wildcard Pattern and the address it Will Point To.
3. Click Create Wildcard. The new hostname appears with a Wildcard badge, and the base hostname no longer offers Create Wildcard.

Keep the wildcard's address current

• In the dashboard: Update IP on the wildcard row, the same as any hostname.
• From a router or script: send a second update with hostname=*.home.example.com alongside the one for home.example.com. See DDNS Update Protocols.

See your wildcards

Choose Wildcards in the filter list.

Remove a wildcard

Click Delete (trash icon) on the wildcard row and confirm. Names under the base hostname stop resolving, and the base hostname offers Create Wildcard again.

Deleting the base hostname does not delete its wildcard. Delete the wildcard too if you no longer want it to resolve.

With the API

With an API key, send POST https://www.certadns.com/api/domains/wildcard with a JSON body:

{"base_fqdn": "home.example.com", "rrtype": "AAAA"}

rrtype is A (the default) or AAAA and must match the base hostname. Add record_ip to give the wildcard an address other than the base hostname's. The answer is:

{"fqdn": "*.home.example.com", "rrtype": "AAAA", "record_ip": "2001:db8::10", "status": "success"}

In the hostname list (GET https://www.certadns.com/api/domains), a base hostname that has a wildcard carries "wildcard_enabled": true.

7. Inputs and Settings

8. Outputs and Results

• A row for *.<base hostname> with a Wildcard badge, its own Current IP, and Update IP, Update Instructions and Delete.
• No Create Wildcard icon on the base hostname while its wildcard exists.
• Lookups for names under the base hostname answer with the wildcard's address.

9. How to Interpret Results

Normal

• anything.home.example.com returns the wildcard's address; a name you added as its own hostname returns its own address.

Worth investigating

• The wildcard shows an old address — the base hostname changed and the wildcard was not updated. Update the wildcard as well.

Common mistakes

• Expecting the wildcard to follow the base hostname. It keeps the address it was created with until you change it.
• Expecting the wildcard to cover the base hostname itself. *.home.example.com covers names under home.example.com, not home.example.com.

10. Common Issues and Explanations

No Create Wildcard icon

You are on the Free plan, the hostname already has a wildcard, or the row is itself a wildcard.

Create Wildcard is disabled, with "Please set an IP address on the base domain before creating a wildcard"

Give the base hostname an address with Update IP first.

"Wildcard already exists for this domain"

The hostname already has one. Delete it first to create it again.

"Base domain not found. Create the base domain first."

The base hostname is not on your account, or is spelled differently.

"Wildcard DNS requires … subscription"

Wildcards need Dynamic DNS Pro or Elite.

11. Limits and Constraints

12. Related Features

• Dynamic DNS — creating the base hostname.
• DDNS Update Protocols — updating the wildcard from a router or script.
• API Keys — for creating wildcards through the API.

13. Updates and Behavior Changes

• 30 September 2026. The Create Wildcard icon is now hidden on a hostname that already has a wildcard, and deleting a wildcard from the dashboard makes it available on the base hostname again. The hostname list returns wildcard_enabled. Earlier versions of this article showed an API response with fields that are not returned.