What is the maximum of nameservers one can enter in Windows? Are there differences in different versions? Linux has a maximum of three, which is set in
# define MAXNS 3 /* max # name servers we'll track */
In this puzzle of Windows limits there isn't much published information.
For example, Microsoft's Configuring DNS client settings says :
From this we can infer that MS considers 25 DNS servers to be "larger" than the default limit. Under normal conditions the limit would apparently be lower.
Although it has been rightly remarked that this number has no direct relation to the number of DNS servers, it seems that the person who designed this interface liked multiples of five.
As a side-note, if you are interested in AD, then Active Directory limits says :
I know that the advanced TCP/IP settings shown elsewhere with capability of many DNS server addresses has been a standard component of every Microsoft Windows DNS client going back to Windows 95 and Windows NT 4, though a DLL or method for entering them may have varied. It may go back even further, but I didn’t have to maintain a Windows IP network with older versions.
I also know that the first three hosts listed are used, because when our ISP’s two hosts were unavailable, the third host that was maintained by another company was used instead.