KEY AREAS
Separate the questions before choosing the work.
Discovery and internal links
A URL needs a path to discovery. Review relevant internal links and the URLs the site makes available, rather than assume a published page has been found.
Response and access
Check what the requested URL returns. A login requirement, failed request, redirect or server error needs a different investigation from a normal page response.
robots.txt
A disallow rule controls crawling by compliant crawlers. It is not a dependable way to remove a page from Google’s index; a blocked URL can still appear without its content being crawled. The robots.txt generator can help draft the file, but review each rule against the access you intend to allow.
noindex
Google needs access to read a noindex rule in the page or response header. Blocking crawling can prevent that rule from being seen. Do not put noindex in robots.txt.
Canonical preference
A canonical identifies a preferred representative for similar content. Google can select a different URL. Check whether links, redirects and sitemap entries agree with the intended version.
Sitemaps and page purpose
Review whether the sitemap lists the intended search destinations. Inclusion helps communicate URLs; it does not guarantee indexing or visibility. Use the XML sitemap generator to prepare a small sitemap from the public URLs you have checked.

