I have no idea about the list on dnsperf.com for example digital ocean dns isn't fast at all, but it is top 5 on the list, and quite a few service on the list doesn't offer to small individual users. Source: almost 2 years ago

Cloudflare (at least for DNS if you don't want other features... See dnsperf.com for why). Source: about 3 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