DNS – DOMAIN NAME SYSTEM
DNS records are stored in DNS servers and work to help users connect their websites to the outside world. When the URL is entered and searched in the browser, that URL is forwarded to the DNS servers and then directed to the specific Web server.
A Record
Generally, A records are IP addresses. The most common DNS record used, the A record simply points a domain to an IPv4 address, such as 11.11.11.11. To set up an A record on your domain all you’ll need is an IP address to point it to.
You can also set subdomains to point to other IP addresses as well, if you run multiple webservers. Finally, a wildcard record, shown usually as ‘*’ or ‘*.yourdomain.com,’ acts as a catch-all record, redirecting every subdomain you haven’t defined elsewhere to an IP address.
CNAME Record
CNAME is a Canonical Name records. It is very commonly used to link a subdomain to a domain’s A record, instead of making 2 A records. In simple words, used to redirect from one domain name to another automatically.
For example, if you wanted abc.yourdomain.com to automatically redirect to your store, you could add a CNAME record to accomplish that.
NS Record
Name server records (NS records) are the DNS records that indicate the authoritative DNS servers for a domain. If you change hosting to somewhere other than where you registered your domain, you would need to update the NS records.
Setting the NS record is therefore a very important part of getting your domains and servers online.
Example: abc.com 86400 IN NS ns1.abc.com
MX Record
MX, or Mail exchange records are used to the mail server that should be used to deliver mail for a domain using SMTP (simple mail transfer protocol). MX records always point to a domain, not an IP address. If a domain doesn’t have an MX record, a sending server will attempt to deliver mail to the domain’s A record instead.
Example : 86400 IN MX 10 mail.domain.com
TXT Record
A TXT record allows you to add text data into your DNS records. A common use is ownership verification. Applications can use this to check information about a service you are running, commonly SPF records, Domain Keys, and DKIM (two other email verification processes).
PTR Record
A PTR (pointer) record, also called a reverse DNS record, resolves an IP address to a domain name. mainly used to check if a server name is actually associated with the IP address from where a connection was initiated. If you want to do a reverse lookup, a PTR record query can help.