Custom First-Party Tracking Domains

A custom tracking domain lets your server GTM container answer on a subdomain of your own site, such as data.yourstore.com, instead of the free *.taglinc.com address. You add one CNAME record at your DNS provider, check it in Taglinc, and point your Google tag at the new address. It takes about five minutes.

Why use your own domain

• Cookies last longer. Requests go to your own site, so browsers treat the cookies as first-party. Safari limits third-party and script-set cookies much more strictly.
• Fewer blocked requests. Ad blockers see a request to your site, not to a known tracking address.
• Works with other Power-Ups. Custom Loader and Cookie Keeper both run on your own domain.

The free *.taglinc.com address keeps working after you add a domain, so nothing breaks while you switch.

How many domains your plan includes

Plan	Custom domains per container
Free, Pro	1
Business, Enterprise	Several (see Server GTM Plans Compared)

Step 1: Pick a subdomain

Use a subdomain of the site you track, for example data.yourstore.com for yourstore.com. Pick a plain name such as data, s or sst. Some blocklists match names like tracking, analytics or gtm, so avoid those.

Use a subdomain, not the main domain itself (yourstore.com), because the main domain already serves your website.

Step 2: Add the CNAME record at your DNS provider

Open your container, go to Domains, and look at Add your own domain. It shows the exact record to create:

Type	Name	Value
CNAME	data (your subdomain)	track.taglinc.com

Copy the value from the Domains page: it is the address of the server your container runs on, and the page always shows the right one.

Where to add it:

• Cloudflare: DNS → Records → Add record. Set the proxy status to DNS only (grey cloud). If the orange cloud is on, Taglinc cannot issue the HTTPS certificate.
• cPanel / hosting panel: Zone Editor → Add Record → CNAME.
• Namecheap, GoDaddy, others: the DNS or Advanced DNS page of the domain → add a CNAME record. Many panels want only the subdomain part (data) in the Name field.

DNS changes usually show within a few minutes, sometimes longer.

Step 3: Check and add the domain in Taglinc

Back on the Domains page, type the full subdomain (data.yourstore.com) and choose Check and add. Taglinc looks up the CNAME record. When it matches, the domain is added and the HTTPS certificate is issued automatically. Only an owner or developer of the container can add a domain.

Step 4: Point your Google tag at the new address

In your web GTM container, open your Google tag and set the configuration parameter server_container_url to https://data.yourstore.com. Then publish the web container. The full steps are in Connect Web GTM to Your Server Container.

If you use the Custom Loader, change the script address in your website snippet to the new domain as well.

Check that it works

• Open your site with GTM Preview, or open your browser's developer tools on the Network tab. Requests such as /g/collect should now go to data.yourstore.com.
• On paid plans, the container's Event Logs show the requests as they arrive. See Using Event Logs and Analytics.

If the check fails

Message	What to do
No CNAME record found yet	The record is missing or has not spread yet. Check the name and wait a few minutes, then try again.
Found a CNAME, but it points to another address	Change the record's value to the one shown on the Domains page.
That domain is already in use	The domain is on another container. Remove it there first.
That address belongs to Taglinc	Use a domain you own, not a *.taglinc.com address.
Plan full	Every domain on your plan is used. Remove one or move to a plan with more domains.

On Cloudflare, also check that the record is DNS only. A proxied (orange cloud) record hides the CNAME. For other problems, see the Server GTM Troubleshooting Checklist.

Remove a domain

On the Domains page, choose remove next to the domain. Requests to it stop reaching your container right away, so point your Google tag at another address first.