I'm trying to setup a simple ARR system. I have 1 ARR machine load balancing between 2 APP servers. I can reach the app sites if i use the server name of the ARR machine. (http://arrserver/app) But i can't do it with its IP address. ( It gives the "Bad Request - Invalid Hostname". In the ARR machine i configured the default site's bindings to "All Unassigned","80" (default values). Do i need to change the binding rule or need additional url rewrite rules? And also, in the ARR server doesn't work. But http://localhost/app works fine.

Thx in advance


The IP address and the Host Header Name are two different entries. IIS is telling you that it doesn't know what site to send the HTTP request to, since when you set the "Host Header Name" field, it allows you to put multiple websites on the same IP and Port. If you can leave it blank, do.

If you can't, the way I've overcome this in the past is to make two websites, one bound to the host name, and the other bound to everything else. The site without Host Header will redirect all requests to the site with the host header flag.

Check out this site: http://www.orcsweb.com/blog/mark-newnam/how-to-set-up-site-bindings-in-internet-information-services-iis/ - it has a good overview of different IIS site binding configs.


Check the host header name on 2 backend servers:

enter image description here

  • Hi @quanta. The two backend servers have no Host Header Names. They are blank. – syloc Oct 14 '11 at 13:49
  • How about the IP Address on the 2 app servers? – quanta Oct 14 '11 at 14:32
  • They are "All Unassigned". They have the default values. Nothing configured here. – syloc Oct 14 '11 at 19:32

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