For example, I got this just now on 3 successive calls:
$ host fly.dev
Host fly.dev not found: 3(NXDOMAIN)
$ host fly.dev
Host fly.dev not found: 3(NXDOMAIN)
$ host fly.dev
fly.dev has address 77.83.140.34
We noticed this because our application has had intermittent outages recently. The main domain is a CNAME to a fly.dev hostname:
$ host fleetweb.standardfleet.com
Host fleetweb.standardfleet.com not found: 3(NXDOMAIN)
$ dig fleetweb.standardfleet.com
fleetweb.standardfleet.com. 60 IN CNAME nikola-fleetweb.fly.dev.
$ host nikola-fleetweb.fly.dev
Host nikola-fleetweb.fly.dev not found: 3(NXDOMAIN)
I would note that it is working sometimes, and returns correctly:
$ host fleetweb.standardfleet.com
fleetweb.standardfleet.com is an alias for nikola-fleetweb.fly.dev.
nikola-fleetweb.fly.dev has address 109.105.222.202
nikola-fleetweb.fly.dev has IPv6 address 2a09:8280:1::1:1eaf
Weāre further adjusting the server to return NOERROR instead of NXDOMAIN when we know about a subdomain, but donāt have anything to return for the query.
I apologize, I thought there was still an issue ā it appears that Google DNS, Cloudflare, and several others seem to work now. I assume the old records timed out and they were able to re-query the flydns.net nameservers.
Assuming api.OURHOST.com is a CNAME for OURHOST.fly.dev, then thatās what we are seeing too. I ran it a bunch of times just now querying Google DNS and there are a handful of failures currently:
# failure in AAAA records
$ host nikola-fleetweb.fly.dev 8.8.8.8
Using domain server:
Name: 8.8.8.8
Address: 8.8.8.8#53
Aliases:
nikola-fleetweb.fly.dev has address 109.105.222.202
Host nikola-fleetweb.fly.dev not found: 3(NXDOMAIN)
Host nikola-fleetweb.fly.dev not found: 3(NXDOMAIN)
# failure in A/AAAA records
$ host nikola-fleetweb.fly.dev 8.8.8.8
Using domain server:
Name: 8.8.8.8
Address: 8.8.8.8#53
Aliases:
Host nikola-fleetweb.fly.dev not found: 3(NXDOMAIN)
# success
$ host nikola-fleetweb.fly.dev 8.8.8.8
Using domain server:
Name: 8.8.8.8
Address: 8.8.8.8#53
Aliases:
nikola-fleetweb.fly.dev has address 109.105.222.202
nikola-fleetweb.fly.dev has IPv6 address 2a09:8280:1::1:1eaf
Thatās supposedly the debugging interface for Googleās resolvers.
Do you know approximately what time this started today? Also, can you get dig a nikola-fleetweb.fly.dev @8.8.8.8 +trace to fail? The host command is surprisingly opaque about what itās doing.
One workaround here is to not use a CNAME for DNS. If you run fly ips list, then set an A record for the IPv4 and an AAAA record for IPv6 itāll work fine. Technically a little faster, even, since thereās only one DNS lookup required.