Understanding DNS concepts
This document contains some concepts and definitions that are related to the internet's domain name system (DNS) and how it affects your usage of IBM Cloud® DNS Services.
DNS zones
A DNS zone is a collection of resource records, which belongs to a single parent instance. All resource records have the zone's domain name as a suffix. You can create, update, delete, get, and list the DNS Zones by using curl commands.
See Managing DNS zones to learn more about how to manage DNS zones.
Permitted networks
Permitted networks are the VPCs that can perform name resolution on the DNS Zone. It is used as an access control mechanism to guarantee that only the VPC that has been added as a permitted network can perform name resolution on the DNS zone.
See Managing permitted networks to learn more.
Resource records (RR)
Resource records (RR) are entries in the DNS zone files. The most common type is an A record that provides a mapping between a name and an IPv4 address.
DNS Services supports the following types of resource records:
A (IPv4 Address Record)
Provides a mapping of a host to an IPv4 address.
AAAA (IPv6 Address Record)
Provides a mapping of a host to an IPv6 address.
CNAME (Canonical Name)
Provides a way to alias a hostname to another hostname or Canonical Name (CNAME).
PTR (Pointer)
Enables reverse DNS lookup, from an IP address (IPv4 or IPv6) to a hostname
MX (Mail Exchange)
This record specifies the SMTP mail server for the DNS zone.
SRV (Service Location)
This record specifies the location of one or more of the servers for a specific protocol and domain.
TXT (Text)
This record is used to hold descriptive text for a given name.
NS (Name Server)
You cannot create this type of record in DNS zone, but you can query for your DNS zone. The data that is returned is statically defined and cannot be changed.
SOA (Start of Authority)
You cannot create this type of record in DNS zone, but you can query for your DNS zone. The data that is returned is statically defined and cannot be changed.