Domain Name System

Lync Server heavily relies on domain name system (DNS) for name resolution and service lookups. Since Lync is always installed in an Active Directory environment, which also requires DNS, this service is typically already in production before the installation of Lync, and therefore simply needs to be configured to meet Lync requirements.

Lync Server utilizes DNS for several purposes. First, there is the requirement for hostname–to–IP address lookups, which is the typical use of DNS. However, Lync Server also uses specialized DNS records to identify particular services. Lync Server is also able to leverage DNS round robin functionality to provide load balancing for specific Lync functions. The DNS record types that are primarily used by Lync are the following:

• A, or host records

• SRV, or service location records

A very basic Lync deployment involving only the core services requires only a few DNS records. However, as additional Lync features and services are deployed in the environment, quite a few additional DNS records might be required. For this reason, the DNS requirements for each Lync feature will be detailed in the various chapters of this publication corresponding to that particular feature. For example, edge services, the Device Update Web service, and Lync Mobility all have specific DNS requirements. In this section, the DNS records required to allow basic Lync functionality are covered.

Lync Server requires registration of the hostname for each Lync server as an internal A record. For Standard Edition, a DNS A record that resolves the fully qualified name of the pool to the IP address of the Front End server is also needed. For Enterprise Edition Front End pools involving a hardware load balancer, a DNS A record that resolves the fully qualified name of the pool to virtual IP address of the load balancer is needed.