Here's my favorite DNS story: https://wdkwwdk.com/posts/outage-stories-dns/ https://wdkwwdk.com/posts/outage-stories-dns/ The TLDR is in most cases DNS records

Here's my favorite DNS story: https://wdkwwdk.com/posts/outage-stories-dns/ https://wdkwwdk.com/posts/outage-stories-dns/ The TLDR is in most cases DNS records with the same name but different record type are expired independent of each other. In the DNS protocol there are two different ways to respond that an answer doesn't exist, with subtle differences. We had a typo in our DNS configuration, that caused No Such Name responses on IPv6 queries... and we weren't using IPv6. No such name means the name doesn't exist for any record type, not just the record you asked for doesn't exist. This caused our resolver to look at it's cache and throw out every DNS record with that name... including ones we had statically configured. We no longer knew how to contact root, so we could no longer do any external DNS queries that needed our root servers.