The client does not see the Internet connection. How to fix?

Question

Domain Name System

There is a Windows server 2012R2 server, 2 network cards (internet, lan)
are still worth Kerio Control, and 3 network adapter (auto settings)
Kerio is configured, it has DHCP, everything is ok there.
I think the problem is with access to adapters or a DNS server.
I want DHCP to be assigned to clients, but for some reason it could not connect. Writes

1 question: Which adapter should be shared? and where to look
Question 2: Do I need to set up a name server? in DNS records? there are all registered IPs that are used