The IIS for two minutes was redirecting from
www.example.com. Nobody fixed it - it was a temporary fault.
There is URL Rewrite 2.0 installed which has one rule which was not changed for years and everything was fine until last Monday. For two minutes there was a redirection loop and the site was down.
HTTP/1.1 301 Moved Permanently Content-Type : text/html; charset=UTF-8 Location : http://www.exaple.com/ Server : Microsoft-IIS/8.5 X-UA-Compatible : IE=edge,chrome=1 Date : Sun, 25 Sep 2016 23:15:11 GMT Content-Length : 142
Event logs are clear - nothing from .NET, aps, system.
Did you encounter something like this before? What could be the reason?