DNS-data: what does it do?

Every domain name (for example 'www.copernica.com') is linked to an IP address. The IP address is a unique address recognition of a network (for example 217.67.229.100). This enabled any computer that is connected to the internet to find the corresponding website. The link between the domain name and the IP address is called the Domain Name System (DNS).

DNS is a client-server-system: a kind of digital "phone book" with DNS data. A client uses the DNS-protocol to request a name or address from the server. The server responds to this request by sending a response. When someone tries to visit a website, contact is made with a DNS-server to find the correct IP address which allows the visitor to view the website. Looking for a number linked to a name is called a 'lookup'. Looking for a name that belongs to a number is called a 'reverse lookup'.

DNS is also used to look for mail servers of a specific domain. The computers that receive email. That is why DNS-data also contain the IP addresses that have permission to send email from a specific domain name. It can happen that your sending IP differs from the registered addresses when your systems are not in order or when you are sending with marketing software or through a third party. This means your authentication is no longer correct (this is a process the receiving mail server will execute when receiving mail from a sending mail server). The receiving mail server notices this as well, causing your email to be refused or getting extra critical reviews from spam filters. Your deliverability will decrease significantly!