QHostInfo模块提供了根据域名查询IP地址的API，并同时提供阻塞式和异步式两种API。

The QHostInfo class provides static functions for host name lookups.

QHostInfo uses the lookup mechanisms provided by the operating system to find the IP address(es) associated with a host name, or the host name associated with an IP address. The class provides two static convenience functions: one that works asynchronously and emits a signal once the host is found, and one that blocks and returns a QHostInfo object.

示例代码如下：

#include <QCoreApplication>
#include <QtCore>
#include <QtNetwork>

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
    auto info=QHostInfo::fromName("www.163.com");
    auto ips=info.addresses();
    for(auto ip : ips){
        qDebug() << ip.toString();
    }
    return a.exec();
}

参考资料：

http://qt-project.org/doc/qt-5/QHostInfo.html