Common issues related to URLs

Overly complex URLs, especially those containing multiple parameters, can cause problems for crawlers by creating unnecessarily high numbers of URLs that point to identical or similar content on your site. As a result, Googlebot may consume much more bandwidth than necessary, or may be unable to completely index all the content on your site.

Unnecessarily high numbers of URLs can be caused by a number of issues. These include:

• Additive filtering of a set of items. Many sites provide different views of the same set of items or search results, often allowing the user to filter this set using defined criteria (for example: show me hotels on the beach). When filters can be combined in an additive manner (for example: hotels on the beach and with a fitness center), the number of URLs (views of data) in the sites explodes. Creating a large number of slightly different lists of hotels is redundant, because Googlebot needs to see only a small number of lists from which it can reach the page for each hotel. For example:
  • Hotel properties at “value rates”:

    https://example.com/hotel-search-results.jsp?Ne=292&N=461

  • Hotel properties at “value rates” on the beach:

    https://example.com/hotel-search-results.jsp?Ne=292&N=461+4294967240

  • Hotel properties at “value rates” on the beach and with a fitness center:

    https://example.com/hotel-search-results.jsp?Ne=292&N=461+4294967240+4294967270

• Dynamic generation of documents. This can result in small changes because of counters, timestamps, or advertisements.
• Problematic parameters in the URL. Session IDs, for example, can create massive amounts of duplication and a greater number of URLs.
• Sorting parameters. Some large shopping sites provide multiple ways to sort the same items, resulting in a much greater number of URLs. For example:

  https://example.com/results?search_type=search_videos&search_query=tpb&search_sort=relevance&search_category=25

• Irrelevant parameters in the URL, such as referral parameters. For example:

  https://example.com/search/noheaders?click=6EE2BF1AF6A3D705D5561B7C3564D9C2&clickPage=OPD+Product+Page&cat=79

  https://example.com/discuss/showthread.php?referrerid=249406&threadid=535913

  https://example.com/products/products.asp?N=200063&Ne=500955&ref=foo%2Cbar&Cn=Accessories.

• Calendar issues. A dynamically generated calendar might generate links to future and previous dates with no restrictions on start or end dates. For example:

  https://example.com/calendar.php?d=13&m=8&y=2011

• Broken relative links. Broken relative links can often cause infinite spaces. Frequently, this problem arises because of repeated path elements. For example:

  https://example.com/index.shtml/discuss/category/school/061121/html/interview/category/health/070223/html/category/business/070302/html/category/community/070413/html/FAQ.htm

Resolve problems related to URLs

To avoid potential problems with URL structure, we recommend the following:

• Create a simple URL structure. Consider organizing your content so that URLs are constructed logically and in a manner that is most intelligible to humans.
• Consider using a robots.txt file to block Googlebot’s access to problematic URLs. Typically, consider blocking dynamic URLs, such as URLs that generate search results, or URLs that can create infinite spaces, such as calendars. Using regular expressions in your robots.txt file can allow you to easily block large numbers of URLs.
• Wherever possible, avoid the use of session IDs in URLs. Consider using cookies instead.
• If upper and lower case text in a URL is treated the same by the web server, convert all text to the same case so it is easier for Google to determine that URLs reference the same page.
• Whenever possible, shorten URLs by trimming unnecessary parameters.
• If your site has an infinite calendar, add a nofollow attribute to links to dynamically created future calendar pages.
• Check your site for broken relative links.