Avatar of Kevin Litman
Kevin Litman
Flag for United States of America asked on

Exchange 2010 NLB Connection Issue

Here is my setup.

2 CAS servers using Windows Network Load Balancing.
2 MBX/HT servers with a DAG setup.

My issue is when I want to take one of the CAS servers offline. If I go into NLB and stop the host then any client that was connected to that host will lose connectivity in outlook and owa. The lost connection can be up to a minute long, which is unacceptable. I maintain a ping of the nlb cluster ip when I stop a host.

Before anyone asks. Yes, I have my CAS Array setup with both CAS servers as members. Yes, I have my DNS A record configured correctly.
ExchangeWindows Server 2008

Avatar of undefined
Last Comment

8/22/2022 - Mon

Configure the NLB on something other than the CAS-machines.

Say you have TMG/ISA or some other appliance doing the NLB, it will then point to either CAS behind it. When a CAS goes offline the new requests will simply go to the available CAS.

If the users connect directly to the CAS that is going offline it will take time before the path to that server refresh over the network. If they however connect to TMG/ISA/Appliance it will direct the traffic behind it.
Kevin Litman

Anybody else have any other suggestions?
Kevin Litman

Log in or sign up to see answer
Become an EE member today7-DAY FREE TRIAL
Members can start a 7-Day Free trial then enjoy unlimited access to the platform
Sign up - Free for 7 days
Learn why we charge membership fees
We get it - no one likes a content blocker. Take one extra minute and find out why we block content.
Not exactly the question you had in mind?
Sign up for an EE membership and get your own personalized solution. With an EE membership, you can ask unlimited troubleshooting, research, or opinion questions.
ask a question
Kevin Litman

My solution to use a hardware load balancer was a better fit for the environment.
I started with Experts Exchange in 2004 and it's been a mainstay of my professional computing life since. It helped me launch a career as a programmer / Oracle data analyst
William Peck

Here's a guide for load balancing with TMG.


Using a hardware load balancer falls under "Configure the NLB on something other than the CAS-machines" as I said in my previous post. Having a ISA/TMG was only a suggestion from my part. I've recently started using Citrix Netscaler VPX for load balancing applications.