Windows Server $2016$ has a $172\mathrm{.}168\mathrm{.}20\mathrm{.}10$ IP address and $255\mathrm{.}255\mathrm{.}255\mathrm{.}240$ subnet mask. Client machine is assigned ip address from DHCP server. After restarting the server, you tried to add a client machine to the domain, but it couldn't be added but you can ping each other machine. What may be preventing the client computer from joining the domain?

The subnet mask

The IP address of the client machine the Windows Server

The DNS server is not configured properly

The DHCP Service not working