What's the Director For?

lync server 2010, Reference

We haven’t shown the Director very much love on this blog. Let’s change that.

In OCS 2007, the “Director” was just a chopped-down Front End server with no default configuration or definite purpose. It often caused trouble by letting users home on it!

In Lync Server 2010 it became its own dedicated server role, and took on a few important duties.

What the Director Does

I think of the Director like a sentry just inside the castle walls. A Director Server (or a Director Pool) sits between the perimeter network and the internal network. Another hop between the Edge Servers and the Front End Servers.

First, a Director authenticates traffic. SIP Requests come in from the Edge Server? The Director authenticates them before they’re allowed access to the Front End.

As a result, Directors are in the perfect position to protect against malicious traffic and DoS attacks. A Director Server can in fact be overloaded from a DoS attack, while the Front End pool keeps on working. (Mark of a good sentry – he goes down fighting.)

Internally, Directors help handle login and traffic redirects between Front End Pools.

The larger your deployment grows, the more functions a Director performs. For instance, Directors improve Lync performance by taking some of the authentication & traffic workload off Front End Servers.

Do You (Really) Need a Director?

Technically speaking, no. A Director IS optional. Most of its functions will run on Front End just fine.

However, the larger your deployment becomes, the more benefit a Director can give you. In Enterprise Edition pools, it can host the Registrar role to help with voice resiliency.

Directors even distribute information about backup registrars through the network, to help with failover.


The Director often confuses people – we get plenty of questions about it. I think that’s because its purpose isn’t any specific function, like Edge or A/V Conferencing. Instead, it assists other servers in performing their roles a little more efficiently.

And because of that, a Director can make your Lync Server deployment a lot better.

Do you use a Director? Where do you find it helps the most?

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