Clarification on Custom Nameservers for many domains

Hello, I am new to Cloudflare and would like to ask the community for help regarding how custom nameservers work. (The Business plan “support” basically just referred me here).

Specifically, my situation is that I host about 300 client websites who currently have their domains connected to my server via the following two [example] custom nameservers:

NS1.EXAMPLE.COM
NS2.EXAMPLE.COM

Additionally, for most of these clients I have custom DNS records set up at the server level (MX, DKIM, DMARC, SPF, TXT, etc.).

I can see how to create these custom nameservers in my Cloudflare account. I also know how to “glue” them to Cloudflare’s IP addresses at my domain registrar.

My questions are:

• Once I add these two custom nameservers to my Cloudflare business account and “glue” them, will all 300 client sites routing through these nameservers automatically start routing through Cloudflare and have all the Cloudflare benefits?

• If so, will all these sites’ existing server-level DNS records be preserved? (MX, DKIM, DMARC, SPF, TXT, etc.)?

• If not, is there any way to set this up through Cloudflare without having to update the NS records for all 300 websites (which would be a monumental effort). I could potentially re-set-up all the other client DNS records, but logging in to hundreds of clients’ GoDaddy accounts is not happening.

Thank you.

Custom nameservers are only necessary if you want your domain to use nameservers under that very domain (typical glue). You don’t need custom nameservers to set up other domains and have them use your own nameservers.

Just make sure the DNS entries are not proxied and that should work fine.

If you want to use Cloudflare’s nameservers, you don’t need custom nameservers either but rather Custom hostnames · Cloudflare for Platforms docs.

Thank you Sandro. I’m still a bit lost, though, unfortunately. I do understand how the Custom Hostnames work in the Cloudflare for SaaS context – as far as routing the domains through Cloudflare via a CNAME record at the domain level.

But as I mentioned I cannot practically update all 300 domains this way – I am essentially stuck with having all these domains routing through the same existing nameservers like NS1.EXAMPLE.COM and NS2.EXAMPLE.COM

Can you elaborate on this? Basically, how would I set this up in my Cloudflare account? Do I need to add each and every domain to my Cloudflare account? Then when these two NS records are connected to Cloudflare all these sites will be using the Cloudflare CDN?

Thank you.

Do you have your own nameservers for your customers?

Yes, all 300 domains are connected to the same two custom nameserver addresses.

So you don’t need custom nameservers. You simply configure the necessary DNS entries for the two nameservers on Cloudflare, make sure they are not proxied, and it should work.

Ok, so just to be clear, in that case all 300 of these domains would “pass through” Cloudflare and would not be using Cloudflare (for CDN, DDoS protection, etc.). Is that correct?

Not even that, the hostnames of the nameservers would be resolved by Cloudflare but DNS itself will still be handled by your original nameservers.

Ok, I see. Thank you. So I guess my original question is – is there a way to actually use Cloudflare for all 300 of these sites, while still having those domains routing through these same two nameservers?

Ehm, that’s why I asked if you use your own nameservers. You said yes, no you say no.

I’m sorry, Sandro. I guess I don’t understand what you’re asking. I have these two nameserver addresses set up at my domain registrar. Then all 300 client domains are currently connecting directly to my server via those same two nameserver addresses.

So you are running your own nameservers then?

Yes, I suppose so.

And you want to keep running them?

I just cannot feasibly update these NS records at all 300 client domain registrars. I’m stuck with them. So I want to continue using those nameserver addresses, but somehow have the sites using Cloudflare, with all the Cloudflare benefits. I don’t know if this is possible, or how it’s achieved.

That is not possible unless you have CNAME setups or are an Enterprise customer.

If you just want to use Cloudflare for your own domain and use your own nameservers, you only need to follow what I wrote earlier.

Otherwise you could check out the SaaS offer, but that’s not exactly nameservers either.

Ok, thank you for confirming that. I suspected that was the case but just wanted to confirm. Unfortunately the Enterprise plans would be way outside my budget.

Anyways thank you for your time and help.

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