subdomains
Today, let’s define the term “fully qualified domain name,” aka FQDN.It can seem like a bit of a complicated term for a simple thing. What’s an FQDN? It’s a whole internet address. Sometimes it might be called a subdomain (I’m guilty of this), or an internet hostname. Think of it as the server name or host name + the domain name. For www.spamresource.com, www would be the hostname or server name, and then spamresource.com is the domain name. So www.spamresource.com is an FQDN, a fully qualified domain name.If somebody asks you if you have a DMARC record for the FQDN email.spamresource.com, you would specifically enter “email.spamresource.com” in a DMARC record lookup tool. This could be called checking for a DMARC record at the FQDN level or at the subdomain level.In the case of sending from a subdomain, like email.spamresource.com, that subdomain would also be considered an FQDN, for purposes of
Subdomains are “sub entries” under your domain name. Sometimes they’re more accurately called hostnames or FQDNs (“fully qualified domain names”) but for simplicity’s sake, I’m mostly just going to call them subdomains here.You’re reading this on Spam Resource, which has a website address of www.spamresource.com, of which spamresource.com is the domain name. If I were going to create a subdomain for my email newsletter, I might choose email.spamresource.com. In this case, email.spamresource.com is a subdomain of spamresource.com.If you send different types of email messages in any significant volume (at least thousands monthly), you might want to consider having separate subdomains for different from addresses for different types of emails that you send.Let’s say you’re Jeremy Bonto, founder of the famous Bontocorp conglomerate, a company that sells a lot of widgets to people, and also has a lot of employees. It is potentially a good practice for Bontocorp to not send