In short. Server log analysis uses recorded requests, verified client identities and HTTP statuses to examine crawler access and response outcomes.

Definition: Server log analysis is the examination of recorded web requests and their response outcomes. For crawler monitoring, it connects a requesting client's identity with the requested URL, request time and HTTP status returned by the server.

Key facts

Apache's Log Files documentation describes an access log that records requests processed by the server; CustomLog controls its location and contents.
Apache's mod_log_config reference specifies %>s for the final response status after internal redirects.
Google's request verification guide provides IP range matching and reverse plus forward DNS checks for identifying requests from Google.
Google's HTTP status documentation treats 304 as unchanged content and 429 as a signal of server overload.

What should a crawler access log contain?

As of 17 October 2026, Apache documents configurable request logging, while Google documents the verification and response handling described below. A user-agent is the identifying information a client reports in its User-Agent request header. Apache's Log Files guide includes this header in its Combined Log Format, alongside the request and response fields.

A crawler-focused configuration assembled from the fields in Apache's mod_log_config reference is:

LogFormat "%a %t %m %U%q %>s %b %{User-agent}i" crawler
CustomLog "logs/crawler_access_log" crawler

Here %a records the client IP address, %t the request time, %m the method, and %U%q the path plus query string. %>s records the final status, %b the response size excluding headers, and %{User-agent}i the reported user-agent. The same reference provides %D for request duration in microseconds and %L for matching an access entry with an error-log entry.

How is a crawler request identified?

The user-agent provides an initial label for filtering requests. Verification then checks whether the requesting IP belongs to the claimed operator. Google's verification guide explicitly addresses requests that falsely claim to originate from Google.

DNS, the Domain Name System, supports lookups between IP addresses and hostnames. Google's manual procedure starts with a reverse lookup of the logged IP. The returned domain must match an approved Google domain; a forward lookup of that hostname must then return the original IP. For automated checks, Google publishes separate address lists, including common-crawlers.json for common crawlers such as Googlebot.

The address field also needs inspection. Apache's Log Files guide explains that an intervening proxy can cause the logged address to represent that proxy. Verifying a proxy address would identify the intermediary rather than the original requester.

How are response outcomes interpreted?

A practical report groups verified requests by URL, time period and final status. Google's HTTP status documentation supplies concrete interpretations: 200 passes received content to the next processing stage, 404 indicates missing content, and 5xx responses or 429 cause temporary reductions in crawling. A 304 indicates that content is unchanged since the previous crawl.

For diagnosis, Apache's mod_log_config reference also defines %X: a value of X records a connection aborted before the response completes. This adds connection information to the response status.

FAQ

Can I identify Googlebot from its user-agent alone?

Google's verification guide addresses impersonation. You can check the logged IP against the appropriate published ranges or complete both DNS lookups.

Does a successful request prove inclusion in an AI answer?

A successful HTTP response alone does not establish inclusion in an AI answer. Google's status documentation places a 200 response before the next processing stage, which for Google Search is the indexing pipeline.

Sources

Check how a page reads to answer engines. Open the GEO score analyzer