MSNBot: Retired Microsoft Crawler Replaced by Bingbot
MSNBot was renamed Bingbot on October 1, 2010. Old msnbot robots.txt rules, msnbot host names, and how to identify Bing requests.
MSNBot was the web crawler of Microsoft’s search engine before Bing. Bing renamed its main crawler to Bingbot on October 1, 2010, and said that it planned to phase out the other MSNBot crawlers soon after. To control Microsoft’s search crawler today, write robots.txt rules for bingbot.
What replaced MSNBot
In a September 2010 post, Bing confirmed its plan to retire MSNBot and replace it with Bingbot. Bing set the change for October 1, 2010, and gave this user agent for the renamed crawler:
Mozilla/5.0 (compatible; bingbot/2.0; +http://www.bing.com/bingbot.htm)The HTTP From header changed from msnbot(at)microsoft.com to bingbot(at)microsoft.com. Bing also said that the crawler IP addresses and the crawl rate stayed the same.
The old MSNBot help address, http://search.msn.com/msnbot.htm, now redirects to Bing’s Which crawlers does Bing use page. The Bingbot guide covers the current crawler.
Old msnbot rules in robots.txt
In the same 2010 post, Bing said that it still honors robots.txt rules written for MSNBot. If a file has separate groups for MSNBot and Bingbot, the Bingbot group takes precedence.
If you want rules that apply to Bing, put them in a bingbot group:
User-agent: bingbot
Disallow: /private/If your file still has an msnbot group, copy its rules into the bingbot group. After that, you can delete the old group.
msnbot in reverse DNS names
Bing crawler hosts still use “msnbot” in their DNS names. Bing’s 2012 verification post shows that the IP address 157.55.33.18 resolves to msnbot-157-55-33-18.search.msn.com. On 2026-10-22, a reverse lookup of 157.55.39.1, an address from Bing’s published ranges, still returned msnbot-157-55-39-1.search.msn.com. A host name of this type belongs to a Bing crawler. It does not show a separate MSNBot crawler.
Identify real requests
Bing documents a two-step DNS method for requests that claim to come from a Bing crawler:
- Do a reverse DNS lookup on the IP address of the request. Make sure that the name ends in
search.msn.com. - Do a forward DNS lookup on that name. Make sure that it returns the same IP address.
Bing also publishes its crawler IP ranges in bingbot.json.
If a request has “msnbot” in its user agent but fails these checks, it did not come from Bing. You can block it at your server or firewall without an effect on Bing search.
Bing runs other crawlers with their own names and tokens, for example AdIdxBot.