I'm using QnetworkAccessManager to make the HTTP request, I want to know when the FQDN is resolved(DNS resolution) to get the IP address or list of IP addresses.
How QNetworkAccessManager selects the IP from the list of resolved IPs to send the request?
Do QNetworkAccessManager keep the cache of DNS resolution?
QNetworkAccessManager uses QAbstractSocket including its ability to resolve host names. QAbstractSocket uses QHostInfo::lookupHost to get list of IPs (QHostInfo::addresses) of specified host. QAbstractSocket tries to connect to each of QHostInfo::addresses until connection is succeeded.
There is no way to know which address was used because QNetworkAccessManager doesn't expose used sockets to the user. You can get full list of addresses using QHostInfo public API.
QHostInfo has internal global cache which stores up to 128 items with max age of 1 minute.