One of the more difficult decisions when using public key infrastructure (PKI)–enabled applications, such as Lync Server 2013, 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 2013 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 ...