Freedom in information representation and large variety of formats are one of the most important features of the Internet. Yandex search engine strives to index and rank correctly all the available documents. However, the situations in which Yandex robots interpret some information in the wrong way and not as the webmaster intended are still possible.
Using frames — <FRAMESET>, <FRAME>, <IFRAME> tags. We do not recommend using frames, as they may interfere with correct ranking: Yandex search robot does not index documents loaded into frames.
Overabundant automatic redirection. Avoid using redirects as much as possible. A redirection is only good in the case if page addresses change for technical reasons and you have to redirect the user to the new address. Refer to the relevant help topic for instructions on setting redirection (301 redirect) from the old page to the new one. Note that, by default, servers use redirect 302 that, unlike redirect 301, does not guarantee the appearance of the redirect target in the search results.
Page addresses. Each page must be available at a unique and permanent address. It is undesirable for page addresses to contain session identifiers. They should be free of cgi parameter lists as much as possible.
Cloaking. Avoid the situations when the search robot indexes some content and the visitor accessing the page will get something completely different. For example, this may happen with site versions intended for different regions. This will be discussed in the “Regionality” section.
Images instead of text. Avoid creation of pages that do not contain text. If the main page of the site is an image that links to the main part of the site and does not contain any text, this may interfere with the site ranking. The reason for this is that most external links lead to the main page of the site. If this page is a textless document, the reliability of document content discovery decreases somewhat.
Soft 404. One of common errors is using, instead of error 404 message (page not found) for non-existent pages, a stub page that returns code 200 (OK). In this case the search engine decides that the page with an incorrect address exists, and does not delete it from the search database. Because of that, indexing of useful site pages slows down.
Site engine; Monitor the site software to ensure that it works correctly. Errors in site scripts may lead to the same pages having different addresses when accessed from different sections. This may affect the site indexing. Besides, the errors in site engines may be used by evildoers (for example, for publishing links to malicious sites).