DNS Record Types

PUBLISHED ON: Thursday, Jul 6, 2023

#
Nameserver records (NS)

NS allow delegation to occur in DNS.

Root server is managed by IANA.

Here, root zone has delegated management of .com by having named servers in root zone pointing at servers that host .com zone.

A maps host (ex. www) to IPv4 address and AAAA maps host to IPv6 address.

C in CNAME stands for canonical.

CNAME creates DNS shortcuts for a given zone, i.e., host to host records.

CNAME reduces administrator overhead.

CNAME records can't directly point at an IP address.

MX records are used to find a mail server for a specific domain.

Here mail.other.domain. ends with a . and thus, is a fully qualified domain name.

If all MX records are of the same priority, then anyone could be selected.

TXT records allow to add arbitrary text to a domain.

This can be used to fight spam by providing additional functionality for proving domain ownership.

TTL stands for time-to-live.

TTL indicates for how long the results of the query can be stored at the resolver server.

TTL is set on DNS records as <number> in seconds.

For less caching issues, when changing records, we can lower TTL values in advance of days or weeks.

Low value TTL	High value TTL
More query	Less query but less control if record changes are needed