Domain Names

1. The browser asks the local/ISP DNS (Domain name server) for an IP address matching the web address. The IP address is the address of a web server. 
2. Typically the DNS might not have an answer, so
   1. It looks at the web address less then www prefix. That is the domain name.
   2. It goes to the whois database to find out the authorised nameservers.
   3. It asks the authorised nameservers the same question from step 1, eg what is the IP address for the web address. (that's what nameservers do)
   4. This new DNS data is often cached for up to 48 hours by the local DNS.
3. Once the browser knows the IP address for a web address, it talks to the webserver, and tells it which web address it wants to fetch, including the whole URL. 
4. The Web browser decodes the whole URL and returns the appropriate page from the appropriate website.

How Domains Work For Email

1. Your email is sent to a Outgoing Mail Server. 
2. The outgoing server asks the local/ISP DNS (Domain name server) for an IP address matching the end of the email address, eg everything after the @ . That is the domain name.
3. Typically the DNS might not have an answer, so
   1. It goes to the whois database to find out the authorised nameservers.
   2. It asks the authorised nameservers the same question from step 1, eg what is the IP address for the domain name. (that's what nameservers do)
   3. This new DNS data is often cached for up to 48 hours by the local DNS.
4. Once the outgoing server knows the IP address for a domain, it talks to the other parties incoming mail server, and tells it which email address it wants to delivery to. 
5. Done

How Domains Work

1. Domains are registered with a Registry
2. The Registry whois primarily contains contact details, expiry dates and authorised nameservers
3. The authorised nameservers convert web addresses, and domain names into IP addresses for Email/Web services

So to Debug Issues...

• In a perfect world, Registry -> Nameservers -> Email server.... But there are lots to choose from at each level, so how do you know what is right?
• A registry whois often lists several nameservers, but they all basically point to mirror images of the same nameserver. You should not have any other nameservers actvite. If your domain name does not point to our nameservers eg ns1.cms-tool.net, then our nameserver config should be set to "External/None"
• If our nameserver config points to some other mail server via the MX record, eg no mx1.cms-tool.net, then you should disable the email services under the Email tab