Windows Server Technologies for High-Availability & Failover

Introduction
Several technologies exist to ensure that the Remote Desktop Services (RDS) infrastructure can be run in a high-availability
configuration. This paper introduces software high-availability options for each of the RDS components and provides links to
further information.
Round robin DNS
Some RDS components can be enhanced for high availability with the assistance of round robin DNS. When DNS lookup of
the server hostname is performed, the DNS server will change the answer for which IP address to try first. In this manner,
different clients will get a different answer, which tends to spread the load across the server pool.
For more information about configuring round robin DNS, go to http://technet.microsoft.com/en-us/library/cc787484.aspx
.
Network Load Balancing
Although round robin DNS can be helpful in supporting high-availability for RDS, in some situations, Network Load Balancing
(NLB) is recommended instead. Because round robin DNS is unaware if a given host is up or down, the client can end up
spending time attempting to contact a server that is offline. NLB allows multiple servers to appear on the network as if they
were a single IP address, and incoming connections are spread over the NLB cluster while ensuring that new incoming traffic
is not sent to an offline cluster member.
For more information about NLB, go to one of the following websites:
• NLB with Windows Server 2008: http://technet.microsoft.com/en-us/library/cc725691.aspx
• NLB with Windows Server 2012: http://technet.microsoft.com/en-us/library/hh831698.aspx
RD Session Host and RD Virtualization Host
Remote Desktop Session Host (RD Session Host) servers and Remote Desktop Virtualization Host (RD Virtualization Host)
servers can be configured to use a farm. RD Connection Broker is essential for this type of deployment and is responsible for
spreading the load across the cluster members.
To see a checklist for creating an RD Session Host farm using RD Connection Broker, go to
http://technet.microsoft.com/en-
us/library/cc753891.aspx.
RD Connection Broker
RD Connection Broker is an essential component for RDS farm deployments. This broker is responsible for specifying which
server incoming clients should be sent to.
RD Connection Broker supports a special high-availability mode. This should be configured when it is desirable to not have
the broker be a single point of failure.
To see a checklist for creating an RD Session Host farm using RD Connection Broker, go to
http://technet.microsoft.com/en-
us/library/cc753891.aspx.
For more information about RD Connection Broker in high-availability mode, go to
http://blogs.msdn.com/b/rds/archive/2012/06/27/rd-connection-broker-high-availability-in-windows-server-2012.aspx
.
2