Hi. Question: Our DNS server will be offline for a 6 hour period and it hosts our A record. We have a CNAME record only in Cloudflare. In summary:
A Record: On company DNS server- test.com
CNAME record in Cloudflare - www.test.com
Will www.test.com still work or will all attempts to access test.com and www.test.com fail? Or will they both work since DNS servers around the internet still have copies?
Thanks!
DNS will fail if the zone hosting your domain is unable to respond to requests for resolution. test.com’s DNS servers hod the record which points www to Cloudflare. People with cached entries might still work for the length of the DNS record TTL, but any new lookups would fail.
Have you considered having Cloudflare just host your DNS? I mean I’d argue for it full time, but at a minimum you could do it for the period before/during/after the maintenance window and adjust your hosting back at the registrar once maint is complete.
Yes, we are likely to go to Cloudflare full time. We are still building the case.
I originally thought adjusting the TTL for the CNAME record to a long period would help keep the cache longer, but my mistake in logic is the request goes to the authoritative DNS first, then the Cloudflare, so if the authoritative server is down, it will never reach Cloudflare to resolve the CNAME request.
The 6 hour maint window seems like a pretty good one. 
But, I feel your pain. 
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