DNS (Domain Name System) is a naming system for computers, services, or other resources. Domain Name System resolves host names to IP address and IP address to host names.
DNS Records
A (Host record) : A record is main record that resolves host name to IP address (Internet Protocol version 4).
AAAA (IPv6 Host record) : AAAA record is main record that resolves host name to IP address (Internet Protocol version 6).
CNAME (Canonical name record): CNAME Recode is an alias record that maps one name to another.
MX Record: Used to identify an email server for a for a particular domain.
NS (Name Server Record): Identifies the name servers for a particular zone.
SOA (Start of authority Record): The Record identifies the primary name server for a DNS Zone.
PTR (Pointer Record): IP address to name mapping.
SRV Record: SRV record identifies the services available in the domain.
DNS Zone Types
There are four DNS Zone Types Primary Zone, Secondary Zone, Subzone, and Active Directory Integrated Zone.
Primary Zone: This is the main zone and has a read & write copy of the zone data. All changes to the zone are made in the primary zone and are replicated in the secondary zones.
Secondary Zone: A secondary Zone is a read-only copy of the primary zone. This zone cannot process updates and can only retrieve updates from the primary zone. This zone can answer DNS name resolution queries from clients, this helps reduce the workload on the primary zone. Secondary zones cannot be active directory integrated.
Stub Zones: Stub zones are like a secondary zone but only store partial zone data. These zones are useful to help reduce zone transfers by passing the requests to authoritative servers. These zones only contain only three records (SOA, NS, and A records).
Active Directory Integrated Zone: Zone data is stored in ADDS rather than in zone files and Replicates DNS Zone information by using ADDS Replication. DNS can use a multi-master replication model, this enables simultaneous editing zone on more than one DNS server.