Break DOWN your DNS knowledge into pieces

The Domain Name System (DNS) provides visitors access to websites using domain names rather than IP addresses.

 

How does DNS work?

DNS translates human-speak (domain names) into computer-speak (IP addresses). Domain names are text-based names used to identify a website or Internet location. IP addresses are strings of numbers used by every computer connected to the Internet to identify a website's location and communicate with other computers and Web servers.
DNS translates the text-based website or location identifier a visitor enters to the number-based IP address of the associated website or Internet location. For example, myweb.com is a domain name. 208.109.80.200  is an IP address associated with myweb.com. DNS translates the domain name myweb.com to the IP address 208.109.80.200
Using DNS, we can enter easily-remembered text-based domain names and reach machine-readable Internet addresses.

How does DNS know which IP address to use?

Each domain name stores its DNS information in a zone file. Large collections of zone files for different domain names are stored on nameservers. Domain names point to nameservers to locate their zone files — to do this, a domain name must point to the nameserver holding its specific zone file.

How do I know which name server to use?

When you register a domain name, the provider will automatically park the domain name and set its name server to  parking servers. If you activate the domain name or make changes to your website's hosting, your hosting company provides the name server names or IP addresses where your domain name's zone file is located. Use this information to update your domain name settings at your registrar. Once you've updated your name servers or IP address, allow 24 to 48 hours for the new information to propagate through the Internet, and then visitors can reach your website using your domain name.
Zone files organize the zone records for domain names and sub domains in a DNS server. Every domain name and sub domain has a zone file, and each zone file contains zone records. These files, editable in any plain text editor, hold the DNS information linking domain names and sub domains to IP addresses. Zone files usually contain several different zone records.

NOTE: Although domain names might have sub domains, the zone files for sub domains are not considered sub-zone. All zone files are separate entities and do not have a hierarchal structure.

The most common records contained in a zone file are start of authority (SOA), name server, mail exchanger, host, and CNAME. These are described below.

• Start of Authority (SOA) — Required for every zone file, the SOA record contains caching information, the zone administrator’s email address, and the master name server for the zone. The SOA also contains a number incremented with each update. As this number updates, it triggers the DNS to reload the zone data.
• Name Server (NS) — The NS record contains the name server information for the zone.
• Mail Exchanger (MX) — The MX record provides the mail server information for that zone to deliver email to the correct location.
• Host (A) — Uses the A record to map an IP address to a host name. This is the most common type of record on the Internet.
• Canonical Name (CNAME) — A CNAME is an alias for a host. Using CNAMEs, you can have more than one DNS name for a host. CNAME records point back to the A record. When you change the IP address in your A record, all CNAME records for that domain name automatically follow the new IP address.
• Text (TXT) — This is an informational record. Use it for additional information about a host or for technical information to servers.
• Service Records (SRV) — SRV records are resource records used to identify computers hosting specific services.
• AAAA — AAAA records store a 128-bit Internet Protocol version 6 (IPv6) address that does not fit the standard A record format. For example, 2007:0db6:85a3:0000:0000:6a2e:0371:7234 is a valid 128-bit/IPv6 address.