OK, this is driving me bonkers.
I had a website at a subdomain, site.domain.com, set up with an A record that pointed to my home IP address with the website running on a NAS device at 192.168.1.122. I have modified the zone record so it is now a CNAME that points to a totally different domain with an IP address outside of my home network.
On my mobile devices, and only on the mobile devices (I’ve tested on my iPhone and iPad and my son’s iPhone), I still pull up the website from a machine on my home network. The really weird thing is that every once in a while, the new site will pop up if I refresh the browser.
When I do a DNS query of my router with
dig @192.168.1.1 site.domain.com from my desktop machine, it pulls up an “A” record–with the IP address of the local machine the website used to be on–and not the CNAME record:
; <<>> DiG 9.10.6 <<>> @192.168.1.1 site.domain.com ; (1 server found) ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 46256 ;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1 ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 4096 ;; QUESTION SECTION: ;site.domain.com. IN A ;; ANSWER SECTION: site.domain.com. 0 IN A 192.168.1.122 ;; Query time: 5 msec ;; SERVER: 192.168.1.1#53(192.168.1.1) ;; WHEN: Wed Jul 08 19:38:50 EDT 2020 ;; MSG SIZE rcvd: 62
The desktop computer is set to query my local DNS server on my network. The mobile devices are set to get DNS from the router at 192.168.1.1. So that explains why the desktop works and the mobile devices do not.
So it looks to me like my router is caching the A record. But how? It’s been well over 24 hours now. I have also rebooted the router to try to clear stuff from the cache.
I have double checked my local DNS zone settings on my local network, also at 192.168.1.122, and those look fine. And querying my local DNS machine also returns the proper value.