DNS: switch to QDnsLookup instead of letting Qt do the lookup (which caches it for 30 sec or so..)

[michaelstingl]

see comment in closed issue:
#203 (comment)

[guruz]

Right now we don't do DNS lookups manually, we rely on QNetworkAccessManager to do it internally for us)
This would involve adding a DNS-lookup step to our ConnectionValidator.
I'm thinking maybe we can't even do this because QNetworkAccessManager only takes URLs but we'd want URL+IP4/6.

One idea would be to patch our Qt to not do caching in QHostInfo (which is used internally by Qt).

[ogoffart]

I don't understand why we would one to do that. Caching the DNS is a required feature, we do lots of query to the network, and we don't want to add a dns query delay between each of them.

[guruz]

I don't understand why we would one to do that.

See linked issues in original post.

Caching the DNS is a required feature, we do lots of query to the network, and we don't want to add a dns query delay between each of them.

There's also the OS-level cache which is I think the one you're talking about. Usually it's invalidated when the OS has a network connection change. QHostInfo does not do this invalidation (although it could with QNetworkConfiguration but that was never implemented)