Windows NLB is built on network level, so 91 is still considered available.Therefore the requst would still be directed to 91. Since the IIS on 91has been down, I always got "Page cannot be displayed error".
Another thing that really confused me is that I always got the error page after trying many times. I thought NLB would dynamically direct incoming requests to different NLB hosts every time. However, it's not that smart. What it does is actually to associate the client computer's IP to a certain NLB host at the first time this client computer sends request to this NLB cluster. This association will always exist unless that certain host becomes unavailable in the network. That's why whenever I try to access the NLB from my computer, the request always goes to 91 and returns me the error page since the IIS service there is down.
Again, thank you for your patience to read down here.
Another thing that really confused me is that I always got the error page after trying many times. I thought NLB would dynamically direct incoming requests to different NLB hosts every time. However, it's not that smart. What it does is actually to associate the client computer's IP to a certain NLB host at the first time this client computer sends request to this NLB cluster. This association will always exist unless that certain host becomes unavailable in the network. That's why whenever I try to access the NLB from my computer, the request always goes to 91 and returns me the error page since the IIS service there is down.
Again, thank you for your patience to read down here.