The DNS servers setting has been part of the Windows TCP/IP setting dialog since the earliest version of Windows as far as I can remember (Windows 95). However, a host may have multiple network adapters and each of them is assigned a set of TCP/IP settings. DNS servers, on the contrary, is a system-wide global setting used to resolve domain names, which shouldn't be per-connection based. In *nix systems, the DNS servers and host suffix setting is configured in the file /etc/resolv.conf.
Why is DNS server setting shown on of the TCP/IP on Windows?