DNS Records

DNS records aka zone files are instructions that live in authoritative DNS servers and provide information about a domain including what IP address is associated with that domain and how to handle requests for that domain

These records consists of a series of text files written in what is known as DNS syntax. It is just a string of characters used as commands that tell the DNS server what to do. All DNS records also have a TTL, which stands for Time To Live, and indicates how often a DNS server will refresh that record.

Most common types of DNS records

• A record

  • the record that holds the IP address of domain

• AAAA record

  • the record that contains IPv6 address for a domain, as opposed to A records which list the IPv4 address

• CNAME record

  • forwards one domain or subdomain to another domain, does NOT provide an IP address

• MX record

  • directs mail to an email server

• TXT record

  • lets an admin store text nodes in the record, these records are often used for email security

• NS record

  • stores the name server for a DNS entry

• SOA record

  • stores admin information about a domain

• SRV record

  • specifies a port for specific services

• PTR record

  • provides a domain name in reverse-lookups

Less commonly used DNS records

• AFSDB record - used for clients of Andrew File System developer by Carnegie Melon. this record functions to find other AFS cells

• APL record - the 'address prefix list' is an experimental record that specifies lists of address ranges

• CAA record - this is the 'certification authority authorization' record, it allows domain owners state which certificate authorities can issue certificates for that domain. If no CAA record exists, then anyone can issue a certificate for that domain. These records are also inherited by subdomains.

• DNSKEY record - it contains a public key used to verify DNSSEC signatures.

• CDNSKEY record - this is a child copy of DNSSEC record, meant to be transferred to a parent.

• CERT record - the 'certificate record' stores the public key certificates

• DCHID record - the DHCP identifier stores info about the Dynamic Host Configuration Protocol and standardized network protocol used on IP networks.

• DNAME record - the delegation name record creates a domain alias, just like CNAME, but this alias will redirect all subdomains as well. For instance if the owner of 'example.com' bought the domain 'website.net' and gave it a DNAME record that points to 'example.com', then that pointer would also extend to 'blog.website.net' and any other subdomains.

• HIP record - this record uses Host Identity Protocol, a way to separate the roles of an IP address, this record is used most often in mobile computing

• IPSECKEY record - this record works with the Internet Protocol Security, and end-to-end security protocol framework and part of IP suite

• LOC record - the location record contains geographical information for a domain in the form of longitude and latitude coordinates

• NAPTR record - the name authority pointer record can be combined with SRV record to dynamically create URIs to point based on a regular expression

• RRSIG record - the resource record signature is a record to store digital signatures used to authenticate record in accordance with DNSSEC

• RP record - this is the responsible person record and it stores the email address of the person responsible for that domain

• SSHFP record - this record stores the SSH public key fingerprints,