I have a Farm with two WFE servers and I would like to set up Network Load Balancing between the two servers BUT there are two Web Applications. Does anyone know of a guide or have experience that may assist particularly in terms of how the NLB relates to Alternative Access Mapping for the two Web Applications?

Many thanks.

  • I would need a little more information to clear your question. You have two web applications that you want your NLB to redirect to your WFE servers equally. What is the issue you are facing? Apr 25, 2016 at 10:43
  • Hi, as mentioned to Andy below, I am unsure how to map the two web applications in Alternative Access Mappings. When I tried mapping both web applications to a NLB cluster url, central admin wouldn't allow it because one mapping already existed. I was wondering if two NLB clusters were required.
    – Des Owen
    Apr 25, 2016 at 10:51

2 Answers 2


NLB itself is fairly dumb, it just directs traffic for you to a server. The server itself then has to deal with the URLs that are served, so you shouldn't need to do anything particular, just configure NLB (ensure that you either allow all ports, or ensure that the ports that your web applications used are enabled for NLB traffic), point both web applications' DNS entries at the NLB virtual IP (VIP) and things should work quite happily. NLB will accept traffic on the VIP and direct it to one of the pair of servers, and SharePoint will then deal with the traffic in the usual way.

  • Thanks Andy. I think my confusion is around how AAM maps to the NLB cluster or clusters. I'm also not sure if I would need two NLB clusters (one for each web application) or a single one. I tried AAM with a single cluster (say, cluster) and couldn't find a way to map the second Web Application using the same cluster. So, if I had a single cluster, and two web applications (webapp1 and webapp2) what would AAM look like in terms of its default zone please? I believe I need to map the cluster url to the web application in AAM.
    – Des Owen
    Apr 25, 2016 at 10:42
  • Don't worry about the AAMs at all. The easiest way to get everything running is to configure NLB to accept traffic on all ports with both servers in the NLB group. That will forward anything that hits the NLB address to one of the two servers. Then, change the DNS entries for all addresses that SharePoint will serve to the virtual IP address of the NLB. NLB forwards the traffic to one of the servers, SharePoint sorts it out when the traffic hits the server itself. If you have SSL and need more than one IP address, just add more to the list of IP addresses that NLB deals with (i.e. more VIPs). Apr 25, 2016 at 11:26
  • Note that you may need to do a bit of binding work in IIS if this is the case as you'll need to remap the bound IP address to one of the NLB VIPs instead. Apr 25, 2016 at 11:27
  • If you have another server you could use as a load balancer, it's also worth considering Application Request Routing (ARR), which is a free add-in for IIS. It seems to work far better than NLB and I find it easier to configure! See iis.net/downloads/microsoft/application-request-routing for details. Apr 25, 2016 at 12:09

One NLB should be enough for this. Let say you have two WFEs, WFE1 and WFE2 and two web applications webapplication1 and webapplication2.

Lets work with first Web Application webapplication1.

You have configured AAM for webapplication1 with an internet name http://internetWebApp1 for internet users and Extranet name http://extranetWebApp1 for extranet users. Both URLs are different.

  1. Now put an entery in NLB to point 50% of the traffic for the requests of http://internetWebApp1 on WFE1 and 50% on the WFE2.

  2. Put another entery in NLB to point 50% of the traffic for the requests of http://extranetWebApp1 on WFE1 and 50% on the WFE2.

Same process can be followed for webapplication2.

SharePoint will automatically assist the requests for both URL's. NLB has only to tell what is the SharePoint server name/IP against that URL

Hope it helps.

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