i have some questions regarding a setup with different Providers for Domain-Registration and Webhosting.
Letís say I want to have a pure domain registration in country 1 with provider A, which points to my managed virtual server in country 2 with provider B.
Is it right, that normally the registered name server of my domain is responsible for ALL un-cached queries regarding my domain?
So if I want to open example.com in my Browser, I first ask the DNS server of my internet provider, he asks a root DNS server for the name server for TLDs with the ending .com, then asks the name server from nic.com for the responsible name server for example.com and then asks the name server for my domain to get the final ip address for example.com?
Sometimes I read that you have to change the different DNS-Records like A-, AAAA-, CNAME-, MX-, etc. to point to another Server. In other cases I read that you should change the name server(s) to point to another server.
Is the difference, that changing the name server affects all kind of queries for my domain, while changing the different DNS-Records allows a more complex DNS setup (e.g. different server for HTTP, SMTP or sub-domains)?
What are realistic down times, when I tell provider 1 to replace his name servers with the name servers from provider 2 for example.com and have determined a TTL of 14400(4 hours)?
Is there a separate down time caused by internal caching techniques from the interacting name servers which overrides the TTL from Provider 1? If yes, how long is this period?
It seems to me that different providers have a different number of name servers. Could this be a problem, e.g. when Provider 1 can set a maximum of 4 name servers, but provider 2 totally has 5 name servers)?
Sorry for that many questions, but I want to avoid making a big mistake.
The number of name servers should not create an issue as long as they all contain the same data. Make sure your domain name does not have name server records attached to it from different providers. This definitely can create a problem. Usually within 15 minutes the primary name server should be throwing off the new records it has for a domain name. If your domain name is located on more then one providers DNS this will cause a problem too. Some service providers keep your domain cached for 48 hours, although most refresh after a couple hours of less time.