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01 Three streams, not one
An answer engine touches a site in up to three ways. It may have crawled the page weeks earlier for its index. It may fetch the page at question time to quote it. And, if the answer shows a citation and the reader clicks, a human visit arrives. The first two are covered by identifying AI crawler traffic; this page, in the network monitoring section, is about the third, which is the only one that brings a reader.
02 What the Referer header carries
The browser sends a Referer header (the historical spelling) on the request that follows a link. Its content is governed by the page's referrer policy. The default in modern browsers is strict-origin-when-cross-origin: a cross-site click sends only the origin, such as https://answers.example, with no path or query. So you can usually tell which service sent a visit, but not which answer or prompt. Some services set a stricter policy and send nothing; native apps often open links without any referrer at all.
| Case | What the log shows | What to do |
|---|---|---|
| Web answer, default policy | Origin of the answer service | Group by origin; map origins to operators |
| Service sets no-referrer | Nothing | Counted as direct; look at landing pages instead |
| Mobile or desktop app | Often nothing | Same; watch for landing pages that only answers link to |
| Link copied into chat or email | The chat or mail client, or nothing | Cannot be attributed; accept the gap |
03 Building the report from access logs
Keep the Referer field
Make sure the balancer or web server log format records Referer and the request path; many trimmed formats drop it.
Classify referring origins
Maintain a short table mapping referring hosts to answer-engine operators, reviewed monthly as services change domains.
Find first requests
Take the first HTML request of each visit (no same-site referrer before it) as the landing page.
Pair with fetches
For each landing page, count the engine's own fetches of it in the same week. A page fetched often but rarely visited is being quoted without clicks.
Publish weekly
Report visits by operator, the top landing pages and the fetch-to-visit ratio, with the blind spots stated under the table.
04 Reading the numbers
A high fetch-to-visit ratio means the page answers the question well enough that readers do not need to click; that is a content decision, not a network fault. A sudden fall in referral visits with steady fetches often means the service changed its referrer policy or began opening links in an in-app browser. A rise in fetches with no visits and no citation may be a crawler misreporting itself, which the signed-request verification method can settle. Caching matters too: quoted pages are fetched repeatedly, and the caching approach for crawler-heavy pages keeps those fetches off the origin.
Always print the blind spots next to the number. Referral traffic from AI answers is undercounted by design, and a report that hides that invites bad decisions.
Agents that browse on a user's behalf are a separate case again: their visits carry no citation click at all and are covered in what AI agent sessions look like.
05 Questions
How do I track traffic from AI answer engines?
Log the Referer header and landing path, map referring origins to answer-engine operators, and count first requests of each visit. Expect undercounting because referrer policies and apps often strip or omit the referrer.
Why do AI referrals show only a domain, not the page?
The default referrer policy in modern browsers sends only the origin on cross-site navigation, so the answer's URL or prompt is never included.
Are answer-engine fetches the same as referral visits?
No. The fetch is the engine reading your page; the referral is a person clicking the citation. Count them separately and compare them.
What does a high fetch-to-visit ratio mean?
The page is being quoted more than clicked. It usually reflects how complete the answer is, not a technical problem.
Can sFlow measure AI referrals?
No. Referrers live inside encrypted HTTP; use balancer or web server logs.