Programatically clear a single DNS cache entry in Windows and Linux in C++

Question

I am wondering if there is a way to programmatically clear a single DNS cache entry in both Windows and Linux. Or if there is some other way to force a gethostbyname call to not use the local cache.

Clearing the entire cache would not be ideal.

Thanks.

Answer 1

I vaguely recall making the request to the cache with the AUTHORITATIVE bit set.

You can't do that with gethostbyname(): you have to call the resolver on UDP port 53.