DNS Records 101

Your internet will never work properly without DNS or DNS Records.

  • In order to navigate to a website you need to convert www.mysite.com to it’s IP address. It’s also highly useful for emails.
  • DNS acts as phone-book of internet helping you to navigates to all the websites you love.

Different Types of DNS Records

A Record

  • 🔵 A record maps 🗺 domain to IP address (IPv4). 😎

AAAA Record

  • 🔵 AAAA record maps 🗺 domain to IPv6 address.

ALIAS Record

  • The ALIAS record maps a name to another name, but can coexist with other records on that name.
  • ALIAS Records map a domain name to another name, which makes it possible to ‘alias’ the root domain. That basically means they can send users searching for a root domain (like a .com) to a different domain name/website—whichever one you want to send them to. It behaves like an A Record, and because A Records don’t have the limitations of CNAME Records the ALIAS doesn’t inherit them.

CNAME Record

  • 🔵 CNAME Record maps 🗺 domain to A record or CNAME record. 😂
  • 👌 Use only when there are no other records on that name.
  • You can think of it as a pointer 👆 in C\C++.
  • A CNAME Record takes priority over any other resource record for a given hostname. As such, a CNAME cannot coexist with any other resource record, such as MX or TXT Records. So if you had these other records/services for your example.blog domain they would cease to work, as CNAME Records always take precedence.
someblog.com.      CNAME   user.github.io.

MX Record

  • 🔵 MX record shows the mail server responsible for accepting email messages on for given domain name.

PTR Record

  • 🔵 Pointer Record maps an IP address to a 🔵 Fully Qualified Domain Name (FQDN).
  • 🔵 Also known as reverse DNS records.

Checking for domain aa.xx.yy.zz

Windows nslookup -type=ptr aa.xx.yy.zz 8.8.8.8
Unix dig -x zz.yy.xx.aa @8.8.8.8

References

  • https://www.namecheap.com/blog/alias-next-generation-host-record/
  • https://support.dnsimple.com/articles/alias-record/

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