All DNS zones on CZDS have the same format, and AFAIK all nTLDs are required to use it. But you're right for ccTLDs -- everyone uses their own format and most don't even allow you to get the zone file. There are some companies that provide similar lists from crawling data though (e.g. https://zonefiles.io/). - Source: Hacker News / about 2 years ago

There are all kinds of ways Google could find out about your site. For many top-level domains, it's possible to just download a list of all domain registrations: https://zonefiles.io/. Source: over 2 years ago

Namecheap advanced DNS settings has an A Record with "photos" as the host and my home IP as the value. Visiting whatsmydns.net and checking the subdomain photos.myserver.com is propagated gives me green ticks. Doing a "dig photos.myserver.com" shows it's pointing to my home IP. Source: about 1 year ago

You should have virtually 0 in the way of downtime. You can check DNS propagation at whatsmydns.net. That will give you a general idea. Source: over 1 year ago

You can monitor DNS propagation with whatsmydns.net Doesn't make it go any faster, but gives you something to watch - haha. Source: over 1 year ago

I am quite new to the whole topic of email security and today I came across whatsmydns.net and searched for my domain. Since then I realized that some DNS records are open to the public (e.g. Verification and SPF) and others maybe are, too (at least not on this website, couldn't get information about my dmarc entry). Source: almost 2 years ago

However, after over 4 days whatsmydns.net and other dns checking tools are still showing the websites as not fully propagated, in addition my Vercel websites are still showing as pending and "Invalid Configuration" and my Zoho Mail console is further showing as the domain name configured and "MX Verification failure". Source: almost 2 years ago