The Domain Name System (DNS) works as a database that links a domain name to the server’s IP address. It provides a way for a computer to accept a name understandable to humans (such as www.hostens.com) and convert it into an IP address. Using DNS records, we can link websites and other services to the necessary server.
Finally, once we enter a website name in the browser, the DNS server will take the hostname (server name) and convert it into a numeric IP address, which the web browser can connect to upload the website files.
Below we will take a look at the most popular DNS records and their purposes.
An address record is used to point a domain or subdomain name to the server’s IP address. We use it to connect a website to the server where its files are. For example, the subdomain, e.g., www.mywebsite.com, needs to have A record of being pointed to the server.
A mail exchanger record that specifies where the domain or subdomain mail service is pointed. In other words, to indicate a domain or subdomain to the particular server where domain mailboxes are created.
A canonical name is used to point a domain or subdomain to another domain or subdomain. It allows us to relate different domains or subdomains to the final destination and adjust only one A record each time you make a change, regardless of how many host records need to be related to that IP address.
For example, if we point www.mywebsite.com to mywebsite.com using CNAME record, it lets us open the website with or without the www subdomain. And when we change the A record of mysebsite.com, the CNAME record will remain functional.
A text record, and we use it for several purposes such as Google, Microsoft, and other systems verification and some specific records intended to increase emails reputation:
Sender Policy Framework (SPF) – shows what servers can send emails using a specific domain name. Ensures mail delivery and prevents a domain from spoofing. Makes sure that messages are not marked as spam and delivered correctly.
DomainKeys Identified Mail (DKIM) – a domain authentication method that allows a sender to ensure that no one uses its domain for deceptive activity. Before sending an email outgoing server creates and automatically ads a digital signature to the email header. A recipient server can verify this signature by looking up the sender’s public key published in the DNS and accept the email with a valid signature.
Domain-based Message Authentication, Reporting, and Conformance) (DMARC) – helps Internet Service Providers (ISPs) to prevent malicious email practices. This record allows senders to specify how to manage emails that do not pass SPF and DKIM authentication.
A service record that points one domain to another using a specific port. Particular services such as VOIP (Voice Over IP) or IM (Instant Message) uses this record.
A record is similar to A. However, it allows pointing a domain or subdomain to an IPv6 IP address while A record uses an IPv4 IP address.
ADDITIONAL DNS RELATED INFORMATION:
DNS records can be managed only in the domain name’s servers system;
All DNS records need time for propagation. This depends on TTL (time to live) time, but usually, it takes up to 1-2 hours;
We can set up different A and MX records for the same domain or subdomain. It means that a website and mailboxes can function from other servers;
Usually, a domain or subdomain has only one A record. However, some specific systems can require setting up more than one A record for a domain or subdomain;
The domain can have more than one MX record that uses different priorities. The lower the priority number is, the bigger an MX record priority is;
CNAME cannot be pointed to the IP address, only to a domain or subdomain;
As an A record destination, only an IPv4 IP address can be used (e.g., 127.0.0.1);
As an AAAA record destination, only an IPv6 IP address can be used (e.g. 0:0:0:0:0:0:0:0).