One of the more difficult decisions when using Public Key Infrastructure (PKI)-enabled applications, such as Lync Server 2010, is the decision to use internal or public certificates. In this context, internal is defined as coming from a Certificate Authority that is not automatically trusted by the operating system, whereas public means one coming from a Certificate Authority that is already present in the trusted root store of operating systems.
Lync Server 2010 uses certificates for the following purposes:
• External or remote user access to audio/video sessions as well as conferencing and application sharing
• Remote user access for instant messaging
• Federation using automatic DNS discovery of partners
• Mutual ...