Since late 2008 EasySSO has been using the NTLMv2 protocol, which is similar to Kerberos in what it tries to achieve, though different in how it works. In general, NTLM is much more forgiving than Kerberos, it will work in all situations where Kerberos will and in many cases where Kerberos-based authentication is not possible, NTLMv2 will still work e.g. various extranet/VPN/firewall/mobile networks environments. In general, NTLM is much easier to configure (hence EasySSO).
Since October 2015 EasySSO has supported both NTLMv2 and Kerberos-based authentication.