Definition

An HTTP status code is the numeric response a server sends after receiving a request, grouped into 1xx informational, 2xx success, 3xx redirection, 4xx client error and 5xx server error ranges. Googlebot uses these codes to decide whether to index, follow or drop a URL.

Google's documentation outlines how it handles roughly the top 20 status codes encountered while crawling. 200 OK signals a successful fetch eligible for indexing; 301 and 308 indicate permanent redirects that pass signals to the new URL; 302, 303 and 307 are treated as temporary; 404 and 410 remove the URL from the index over time; and repeated 5xx responses can reduce crawl rate and lead to deindexing if they persist. Other codes such as 429 Too Many Requests prompt Googlebot to slow down its requests for the affected host.

Examples

• Permanent redirect after a URL change

  A site moves `/blog/post` to `/articles/post` and returns 301 on the old URL. Google transfers signals from the old URL to the new one over time.

• Server overload during a crawl

  A retailer's server returns 503 responses during a sale-day spike. Googlebot reduces its crawl rate, and if 503s persist for days the affected URLs can drop out of the index.

Sources

• Google Search Central — HTTP status codes, network and DNS errors

Related terms

• 301 Redirect
  A permanent redirect — an HTTP 301 status code telling clients and search engines that a URL has moved permanently to a new location.
• 302 Redirect
  A temporary HTTP redirect (status 302 Found). Search engines keep the original URL indexed because the move is signalled as temporary.
• 404 Error
  An HTTP 404 "Not Found" response, indicating the requested URL does not exist on the server. Google drops 404 URLs from its index over time.
• Soft 404
  A URL that returns an HTTP 200 status but displays content telling the user the page doesn't exist. Google treats it as a 404.
• Redirect Chain
  A sequence of two or more redirects between an original URL and the final destination. Each hop adds latency and risk of signal loss.
• Crawl Error
  A condition that prevents Googlebot from successfully fetching or processing a URL, such as a server failure, DNS issue or HTTP error response.

Where QueryCatch uses this

• SEO Audit
• Crawling & Indexing