is DNS Manager suitable for domains not pointed to Linode?

I have some domains on the Linode DNS, the ones that point to Linode servers, but most of my other domains are on other DNS managers. I have been in the process of moving them all to PointHQ (the non-Linode ones).

Last night PointHQ suffered a massive DDOS attack that left all 5 of its nameservers down. This means all my websites that I use PointHQ for went down. Its the first time I experienced websites going down because of nameservers going down, it never occured to me this could happen, thats why they have 5 nameservers around the work right? So I know its possible that if all my domains were with them then ALL my customer websites would go down, which is what I am trying hard to achieve (not all eggs in one basket).

So now it's made me realise I should not rely on just one nameserver company.

So I wondered if Linode's DNS manager is a suitable DNS manager for non Linode servers? I can't see a reason why not but wondered if anyone knows of any reason it should not be used for non-Linodes.

It has some limitations compared to something like PointHQ which is why I dont use it as my primary DNS manager, but I think suitable for a backup.

I am in the process of writing my own domain database system and thought I could tap into PointHq and Linodes API system to create domains zones simultaneously on both providers rather than add Zones twice everytime.

Thanks