CNAME Question

If you were to add A records in your zone for those two hosts that point to the same addresses as ns1/ns2.linode.com, and you provided your registrar with the IP addresses of those nameservers, then it would work as long as nothing changed.

But whenever Linode moves a nameserver, you're screwed until you happen to notice. And when you do, it'll take two days to fix.

The reason for the two days – and the reason for the italic bit in the first paragraph -- is that the situation in which your nameservers are within the domain they're authoritative for requires the root servers for the top-level domain (say, .com) to not only serve the names of the nameservers in question but their IP addresses as well; otherwise, a resolver that doesn't know anything about mydomain.com would ask for mydomain.com's nameservers and would be told "ns1.mydomain.com" which wouldn't help in the least because it still wouldn't know where mydomain.com's nameservers were to look up "ns1".

And root servers' NS entries tend to have two-day TTLs, so when those change and you notice, it'll be two days before the rest of the Internet fully catches up.

Being able to avoid those extra records (called "glue records") is a benefit, and having to track the IP addresses of Linode's nameservers is a pretty big risk. Just use ns1/ns2.linode.com, or run your own nameservers in your own domain if you realllllly don't want anyone to see "linode.com" in your zone.