Re: IPv6 readiness
One caveat with a dual-stack I have encountered. If you set up IPv6 on your LAN, but do not have IPv6 connectivity, yet, you will get long waits during DNS lookup. This is because Ubuntu enabled IPv6 in the resolver, which will cause it to query for AAAA records before falling back to A records. If a site has no AAAA records, you wait until your resolver asks for A records. This can be quick if the site's DNS answers negatively for the AAAA records quickly. But any slowdown causes much longer waits because the resolver tries AAAA 2 or 3 times before trying A records. If the site does not answer AAAA (some cases of this), then the delay can be significant (up to 30 seconds or so). If the site gives a positive answer for AAAA records, then things go from bad to worse if you can't reach their IPv6 addressed host. The resolver would get the IPv6 address, and the application will try to connect. Since the resolver only asks for AAAA records, and gets them, that is all that the application gets. It would have to ask the resolver specifically for IPv4 addresses as a fallback. How the application handles this can vary. Some may do very bad.
Mask wearer, Social distancer, System Administrator, Programmer, Linux advocate, Command Line user, Ham radio operator (KA9WGN/8, tech), Photographer (hobby), occasional tweetXer
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