The default setting is GoodAvailability, which translates to 6 or fewer logs
BestAvailability (12 or fewer logs missing) and Lossless (0 logs missing).
Host or Local Candidate – The actual IP address bound directly to the remote client’s host operating system. This could include multiple candidates as the remote host could contain multiple physical or virtual network adapters including any active VPN clients. Most often this will be a single IP address of the active interface on a Lync client’s workstation.
Reflexive or STUN Candidate – The public IP address assigned to the client’s immediate firewall perform network address translation. In most home networks this would be the public IP addresses assigned by an ISP (either dynamically or statically) to the premises modem or router, depending on the type of service.
Relay or TURN Candidate – The publically accessible IP address assigned to the media relay server which is allocated to the client. In Lync Server this is the public IP address assigned either directly to the external A/V Edge interface or the public IP address allocated to a NAT device (e.g. firewall) which is performing static network address translation to a private IP address assigned directly to the Edge Server. In the event that an Edge Pool is deployed then this would be the IP address of one of the individual servers in the pool.