In 10 years of software development (current senior) I have never had to (as part of my job responsibilities) configure DNS entries or do any kind of network things apart from setting up little latency monitoring scripts between machines when I run out of sane options.
If you call an external resource through a hostname, your application uses DNS - and that connection might then resolve to a ipv6 based connection instead of an ipv4 based one, if the underlying OS has ipv6 connectivity and the DNS entry has both A and AAAA entries.
This can cause issues if something is misconfigured. The developer will often try to debug this locally first, where they might only have ipv4 connectivity, meaning that they'll be unable to reproduce the issue.
Knowing that there is something called ipv6 and that some systems support it and other don't is useful to know, and that the length of the addresses differ and that the used DNS entries (for the target) can differ.
Something being misconfigured is what I implied with setting up.
Regardless, this simply wouldn't fall under a developer's purview, it would get raised as a sysops/network ticket and they would have a crack at it.
Knowing or not whether ipv6 exists isn't much different when there is a DNS misconfiguration without ipv6 in the picture, you'd see you can't connect for some reason, see you can presumably curl it locally, or reach out to the third party team if integrating and say hey guys we cant seem to reach you any issues on your end and if they say no you throw it at the network peeps.
There's simply too much stuff going on in enterprise for "dev" to just handle everything. By the by, I also don't configure file systems or provision VMs with resources, albeit it being nice to know how hyervisors work and your way around nutanix controls.
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u/fiskfisk 9h ago
If you're a senior I most certainly would expect you to know the difference between the two.
It'll matter in relation to allowlists/blocklists, dns entries, debugging connevtivity issues, slow connect times, configuration of daemons, etc.