A webserver I manage is running Ubuntu 14.04 and is configured for dual stack - ipv6 & ipv4. It is my understanding that ipv6 connections have first priority after which it should fall back to ipv4.
Curiously, when inspecting the Apache server logs, I'm can see the two protocols being used alternately for connections from my office desktop which is ipv6 capable. One minute it uses ipv6, the next ipv4 with seemingly no rhyme or reason to why it chooses one or the other.
There are no apparent problems here - I'm just wondering what factors cause one protocol or the other to be used at different times when nothing has changed that I am aware of?