C-Ares is used for asynchronous DNS resolution. This is the primary name resolution library in Wireshark.
If this library isn’t already installed or available as a package for your platform, you can get it at http://c-ares.haxx.se/.
C-Ares is cross-compiled using MinGW32 and is available at http://anonsvn.wireshark.org/wireshark-win32-libs/trunk/packages/.