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by zoky 760 days ago
Ok, since I’m obviously not nerdy and/or cynical enough to get the joke, what exactly is wrong with DNS? None of the links seem to indicate what exactly the problem with it is.
6 comments

It's not DNS. There's no way it's DNS. It was DNS.

https://medium.com/adevinta-tech-blog/its-not-always-dns-unl...

Discussed here:

It's not always DNS, unless it is - https://news.ycombinator.com/item?id=38719126 - Dec 2023 (73 comments)

I think it’s implied that it’s been zero days since the underlying cause of some such problem turned out to be DNS related. The number zero being hard coded implies that the root of the problem is always DNS. But, let’s give MTU its due.
Lately, MTU has gotten up my list of things to check when stuff goes down.

It seems carriers can't get their MTUs straight as of late, especially on MPLS links...

I really thought we had this figured out 20 years ago...

Two days ago one (!) User reported they got \\contso.com\dfsroot\profiles\user inaccessible (with errors loading the desktop etc).

For me the path was accessible, logging on the same server proved the path was accessible, 3 hours of the proper troubleshooting confirmed everything should work. But yet.

Skipping short the circumstances, one of (the 6 total) DCs decided what... DNS server isn't worth running. And for this one user DFS (last changed at least two years ago) decided to fall back to the file server from 2018, which, of course, pointed the DFS target to a no longer existant share.

Of course it wasn't DNS in this case. It was the DNS in this one.

DFS-N != DNS

a.) lack of monitoring for running services b.) cruft/old configurations

It was inavailable DNS server which triggered changing to an old DFS-N server. People on the same RDS server were working fine and did for literally years.
As someone who administers DNS servers, I'm going to guess this is due to DNS being the first thing that gets blamed when something goes wrong; and it is almost never DNS.
That's the point, but often in many network issues, the name resolution is the root cause of the problem. Not necessarily the DNS itself. Sometimes the /etc/hosts is more than enough to cause headaches!
I've certainly added a hostname to an /etc/hosts file for testing and forgotten.

Nothing makes sense, where is this address coming from? Oh. It was me. I put it there.

A DNS misconfiguration is often the root cause of an issue. Hence the saying “it’s always DNS”.
"It’s always DNS" is basically tongue-in-cheek expression, because DNS issues are so frequently the cause of weird outages.

Almost anything you do on the internet (or local network) depends on DNS functioning correctly. DNS can get complex quickly - multiple servers (caching/authoritative/recursive) and protocols = lots of opportunities for something to be misconfigured. Cached entries in particular can be a nightmare if something gets outdated - it takes time for an update to a DNS record to propagate to all the other DNS servers on the Internet. All kinds of other random services etc depend on DNS records being correct and DNS working. When there’s an issue it’s not always immediately apparent that a DNS problem is the root cause, leading to lots of time chasing your tail/tearing your hair out trying to figure out what the heck broke.