WHM New Account DNS Settings

[Matt]

In other words, when you create an account in WHM and check "Use Domain Registry Nameservers" it is going to do a WHOIS on your domain and use the nameservers that your domain currently is using, which is usually a bad idea. Generally you want it to create your account with the nameservers that have been configured here. usually ns1/ns2.glowhost.net (or similar) or if you are a reseller, ns1/ns2.yourhosting.com

So in regards to:

If I'm creating a new site for someone whose domain is parked somewhere else, and I don't want the domain to point the the new site until it's complete, I'd think to check the "Use the nameservers specified at the Domain's Registrar (ignore locally specified nameservers)" checkbox.

It doesn't matter if you check the box or not, since it is at the registrar / registry where you decide when to point the domain to your server. The DNS zone here does not act authoritatively until your Nameserver have been pointed to it.

If you check the box to use the registry nameservers then when you update your nameservers at your registrar, you are going to have to use the DNS editor in WHM to use your reseller nameservers instead of the ones that USED to be configured at the registry before you pointed your nameservers to the reseller hosting account.

Meaning the registry and your local zone must match in regards to the NS entries. By default, your zones are set to match the nameservers that you will set on your domain, when you are ready to resolve the site. Checking the box overrides this default and uses what you currently have instead of what you are going to be using, which adds an additional step to making your site work.

And while I'm here, what does "Overwrite any existing DNS zones for the account" do?

It means that sometimes WHM will have a DNS zone on the server that was not properly removed at some point in the past. When you try to create a new account, if a zone exists WHM will not allow you to create the account until the zone has been deleted. This new option allows you to overwrite the existing zone instead. Check this box if account creation fails due to WHM complaining about finding a zone for this domain.

Does that answer everything?