Let's assume the DNS resolver and the target server both support dual stack configuration. The resolver will then send DNS queries for A and AAAA RRs. As the server supports both, it will replies with the A RR and the AA RR. So which IP adressing will be used for the connection ? The first one that responses ? Can it be defined/configured ? asked 18 May '16, 11:53  thierryn |
One Answer:
Depends on the stack and the application. Usually IPv6 has preference, which means the AAAA record is used (if an answer record is returned), otherwise it'll use IPv4 (again, if the answer record is returned). There are applications like web browsers who support "Happy Eyeballs" (RFC 6555), which then tries to use the faster connection by trying to send a SYN to both IPv4 and IPv6. answered 18 May '16, 14:52  Jasper ♦♦ |
