| About DNS |
| The Domain Name System (DNS) is a hierarchical naming system for computers, services, or any resource connected to the Internet or a private network. It associates various information with domain names assigned to each of the participants. Most importantly, it translates domain names meaningful to humans into the numerical (binary) identifiers associated with networking equipment for the purpose of locating and addressing these devices worldwide. An often used analogy to explain the Domain Name System is that it serves as the "phone book" for the Internet by translating human-friendly computer hostnames into IP addresses. For example, www.example.com translates to 208.77.188.166. |
| SOA record
The first record of each database file is the SOA record (Start of Authority). Specifies authoritative information about a DNS zone, including the primary name server, the email of the domain administrator, the domain serial number, and several timers relating to refreshing the zone. |
| A record. A records resolve domain name into IP address.
We can say that record is the most important function, since this constitutes the IP address of each host and consists of 32 bits. Each Internet host has a unique IP address so that other machines can connect to it. |
| MX record.
The second most important would be the MX record. This is going to specify the domain name ready to receive email. Each MX record point to the A record. |
| NS record. Delegates a DNS zone to use the given authoritative name servers. |
| CNAME record. Specifies that the domain name is an alias of another. When a DNS resolver encounters a CNAME record while looking for a regular resource record, it will restart the query using the canonical name instead of the original name. |
| PTR record. PTR records resolve IP addresses into hostnames. |
| TXT record. TXT record allows an administrator to insert arbitrary text into a DNS record. For example, this record is used to implement the Sender Policy Framework (SPF) specification. |
| SPF record. SPF is an e-mail validation system designed to prevent e-mail spam by addressing a common vulnerability, source address spoofing.
SPF allows administrators to specify which hosts are allowed to send e-mail from a given domain by creating a specific DNS SPF record in the public DNS. Mail exchangers then use the DNS to check that mail from a given domain is being sent by a host sanctioned by that domain's. |
