What is a DNS record?

A DNS record is a single entry in a DNS zone that stores information about a domain and answers one specific question: what to do with this domain name.

In simpler terms: a DNS record is the rule by which DNS understands where and how to route requests.

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#Why DNS records are needed

DNS by itself is a system. And DNS records are the data stored within it.

DNS records are what tell DNS:

• which IP a domain points to
• where the mail server is located
• which DNS servers serve the domain
• other service information

Without DNS records, DNS would not know what to answer.

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#Where DNS records are stored

DNS records:

• are stored in a DNS zone
• are served by authoritative DNS servers
• are configured by the domain administrator

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#The most important types of DNS records

#A record

Links a domain to an IPv4 address.

Example:

example.com -> 93.184.216.34

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#AAAA record

Links a domain to an IPv6 address.

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#CNAME

Indicates that a domain is an alias for another domain.

Example:

www.example.com -> example.com

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#MX

Indicates which servers accept mail for a domain.

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#NS

Shows which DNS servers are responsible for the zone.

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#TXT

Stores arbitrary text (often used for verification, SPF, DKIM).

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#What a DNS record usually contains

Every DNS record includes:

• a name (a domain or subdomain)
• a record type (A, MX, CNAME, etc.)
• a value (IP, domain, text)
• TTL: how long the record lives in cache

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#An important point for an interview

• a DNS record is not a domain
• one domain can have many DNS records
• DNS records can be changed without changing the domain name

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#Real-life example

DNS records are like lines in a phone book:

• a name
• a contact type (mobile, work)
• a phone number

DNS is the book, DNS records are the entries in it.

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#Short interview answer

Remember this formulation:

A DNS record is an element of a DNS zone that holds information about a domain and defines how DNS should handle requests for that name, for example linking it to an IP address or a mail server.