What is DNS records and what are it for?

Today we are going to talk about DNS records , what they are, what they are for and, above all, clear all the doubts that many users have about them. The first thing to know is that DNS records are mapping files or systems, which tell a DNS server to which IP address a particular domain is associated.

Instead of entering the IP address of a web server that would be more difficult to remember, we enter the name of the website, and our website automatically shows us the browser. This occurs because when we enter the website name in the browser, the browser itself consults with the DNS server configured in the operating system, to which public IP address corresponds that web name we have written.

We also have to be clear that it not only serves this only, but also tells DNS servers how to handle requests that are sent to each domain name. That is, an administrator of a DNS server, can indicate that the name we have entered in the browser and query on the DNS server, which is redirected to the IP that the administrator wants. This is widely used in schools and businesses to prohibit access to certain websites.

Funcionamiento DNS

DNS records

DNS records are different strings of letters that are used to indicate certain actions to the DNS server. These letters are also known as DNS syntax. Next, we will see a list of the different DNS syntaxes that exist:

  • A : When we see the “A” record, it refers to the IPv4 address of a web server and is the most typical of finding us on DNS servers.
  • AAAA : When we see the “AAAA” record, it refers to the IPv6 address of a host. It is the same as the “A” register, but referring to an IPv6 address and not IPv4.
  • CNAME : When we see the “CNAME” record, it refers to an alias from another domain. That is, its function is to make a domain an alias of another domain. Typically, these types of records are used to associate new subdomains with existing domains in registry A.
  • MX : When we see the “MX” record, it refers to a list of mail exchange server that should be used for the domain.
  • PTR : When we see the “PTR” record, it refers to a network termination point. That is, the DNS syntax is responsible for mapping an IPv4 address for the CNAME in the hosting.
  • NS : When we see the “NS” record, it refers to which name server is authorized for the domain.
  • SOA : When we see the “SOA” record, it refers to the beginning of authority. This record is one of the most important DNS records because it saves essential information such as the date of the last domain update, other changes and activities.
  • SRV : When we see the “SRV” record, it refers to a service. That is, it is used for the definition of a TCP service in which it operates in the domain.
  • TXT : When we see the “TXT” record, it refers to a text. That is, it allows administrators to insert text in the DNS record. This is used to leave notes about domain information.
  • SPF : When we see the “SPF” record, it refers to which servers are authorized to send emails with our domain.
  • LOC : When we see the “LOC” record, it refers to the physical location of the server. That is, these types of records are used to indicate the latitude, longitude and height above sea level of the physical location of the server.
  • MB : When we see the “MB” record, it refers to the name of the email domain. This record is currently experimental.
  • MG : When we see the “MG” record, it refers to the members of an email group. This record is currently experimental.
  • MR : When we see the “MR” record, it refers to the popularity of an email domain. This record is currently experimental.
  • NULL : When we see the “NULL” record, it refers to a null resource. This record is currently experimental.
  • HINFO : When we see the “HINFO” record, it refers to the details about the host hardware and software.
  • MINFO : When we see the “MINFO” record, it refers to information about an email inbox. This record is currently experimental.
  • RP : When we see the “RP” record, it refers to information about domain managers.
  • ANY : When we see the type of query “ANY”, it refers to all the information of all types that exists.
  • AFSDB : When we see the “AFDSB” record, it is specially designed for AFS clients.
  • NAPTR : When we see the “NAPTR” record, it refers to an extension of the A record that allows you to use search patterns.
  • KX : When we see the “KX” record, it refers to Key Exchanger and allows cryptographic keys to be managed.
  • CERT : When we see the “CERT” record, this record saves certificates.
  • DNAME : When we see the “DNAME” record, it indicates aliases for entire domains.
  • OPT : When we see the “OPT” record, it refers to a pseudo record of the scope of DNS extension mechanisms better known as EDNS.
  • APL : When we see the “APL” record, it refers to “Address Prefix List” and serves to list ranges of addresses in CIDR format.
  • DS : When we see the “DS” record, it refers to “Delegation Signer” and serves to identify areas with DNSSEC signature.
  • SSHFP : When we see the “SSHFP” record, it refers to “SSH Public Key Fingerprint” and shows the fingerprint for the SSH keys.
  • IPSECKEY : When we see the “IPSECKEY” record, it contains a password for IPsec.
  • RRSIG : When we see the “RRSIG” record, it houses a digital signature for DNSSEC.
  • NSEC : When we see the “NSEC” record, it interconnects zones signed in DNSSEC.
  • DNSKEY DNS : When we see the “DNSKEYDNS” record, it contains a public key for DNSSEC.
  • DHCID : When we see the “DHCID” record, it links domain names with DHCP clients.
  • TLSA : When we see the “TLSA” record, this record establishes a link known as TLSA with a domain name.
  • SMIMEA : When we see the “SMIMEA” record, this record establishes a link known as S / MIME with a domain name.
  • CDS : When we see the “CDS” record, this is a copy of a DS record.
  • CDNSKEY : When we see the “CDNSKEY” record, this is a copy of a DNSKEY record.
  • OPENPGPKEY : When we see the “OPENPGKEY” record, it shows public keys.
  • TKEY : When we see the “TKEY” record, it allows the exchange of secret keys.
  • TSIG : When we see the “TSIG” record, it is used for authentication.
  • URI : When we see the “URI” record, it shows the assignment of host names to URLs.
  • CAA : When we see the “CAA” record, it specifies the possible certification authorities (CA) for a domain.

After seeing what a DNS record is, what it is for, and how it can help us, we have to be clear that the different types of DNS records do not have to worry the end user, but who has to manage all these records and Some more that are not listed, is the administrator of the DNS server. This administrator must know very well what each DNS record is for and what he can do or not do with each record. For end users, you have to know that normally DNS servers if you have not changed them, are those of the ISP that offers you the internet. If you have any questions, leave us a comment and we will resolve it.