Glossary

Tracking domain

The domain that logs the click and serves the landing page. Why keeping them on the same domain is the whole mechanism.

A tracking domain is the domain that logs the ad click and serves the landing page that receives it.

The rule that matters

The click and the page must be on the same domain:

Ad → go.example.com/offer  → Set-Cookie: cid=... (go.example.com)  ✓
Ad → track.other.com → redirect → example.com/offer → cookie lost   ✗

Two reasons:

  1. ITP and third-party blocking act on cookies set from a domain different from the page’s. Same domain, no block.
  2. Redirects lose identifiers. Every hop drops a share, and the loss is concentrated among users with the strictest browser settings — the same users who are hardest to measure anyway.

What a good tracking domain setup looks like

  • One domain you control (a subdomain of your site, or a dedicated domain).
  • The landing page served from it, not redirected to another domain.
  • The identifier set server-side, HttpOnly, in the same response.
  • A default/fallback for requests that do not match any campaign, so the domain never returns an error to a visitor.

Last updated: 2026-09-21

FAQ

Should I use my main domain as the tracking domain?+

It works and it is the most first-party option possible. A separate domain you own is usually preferred: it keeps marketing pages out of the main site, and a browser classification problem on one domain does not affect the other.

Keep reading

Tracking identifiersHow a click becomes a record you can act on: UTM parameters, click IDs and first-party cookies. What each one identifies, and where each one breaks.Landing pageThe page an ad points to. In a measurable setup it is served from the tracking domain, in HTML, so the click survives to the form.

Ready to find out what
converts, for real?

Free to start.

Start free →