DNS Records & DNS Zones

DNS Records

Record Type	Use
SOA (Start of Authority)	The first record in any DNS database file is the SOA. It defines the general parameters for the DNS zone, and it is assigned to the DNS server hosting the primary copy of a zone. There is only one SOA record, and it is the first record in the zone database file. The SOA record includes parameters such as the authoritative server and the zone file serial number.
NS (name server)	The NS resource record identifies all name servers that can perform name resolution for the zone. Typically, there is an entry for the primary server and all secondary servers for the zone (all authoritative DNS servers).
A (host address)	The A record maps an IPv4 (32-bit) DNS host name to an IP address. This is the most common resource record type.
AAAA (quad-A)	The AAAA record maps an IPv6 (128-bit) DNS host name to an IP address.
MX (Mail Exchanger)	The MX record identifies servers that can be used to deliver e-mail.
CNAME (canonical name)	The CNAME record provides alternate names (or aliases) to hosts that already have a host record. Using a single A record with multiple CNAME records means that when the IP address changes, only the one A record needs to be modified. Common uses of a CNAME record include: Adding the alias of www for Web servers. Users typically contact the Web server using a name like www.westsim.com instead of using the actual server name. Associating a server with the domain name itself. For example, create a CNAME record with a blank name to allow a specific host to be identified with the domain name (such as westsim.com).
DNAME (Domain Alias)	The DNAME record provides alternate names (or aliases) to domains that already have a host record.
SRV (service locator)	The SRV record is used by Windows Server 2008 to register network services. This allows clients to find services (such as domain controllers) through DNS. Windows 2008 automatically creates these records as needed and during domain controller installation.
PTR (pointer)	In a reverse lookup zone, the PTR record maps an IP address to a host name (i.e. "points" to an A record). Where IPv4 PTR records are created in the in-addr.arpa namespace, reverse lookup zones for IPv6 addresses should be created in the ip6.arpa namespace. (Note: When you manually create an A record, you can choose to create the corresponding PTR record at the same time. Creating the PTR record will fail if the reverse lookup zone does not exist.)
WINS and WINS-R resource records	Add these records to a zone when you want to allow DNS to use WINS resolution. The WINS resource record allows DNS queries that fail to resolve to be forwarded to the WINS servers in the WINS resource record. The WINS-R resource record allows the resolution of a reverse query that is not resolvable through DNS.

DNS Zone

Zone Type	Description
Primary	The primary zone is the master copy of a zone database. The primary zone is the only writeable copy of the zone database. Changes to the zone can only be made to the primary zone. The server that holds the primary zone is called a primary server. Each zone can have only a single primary zone server. Zone data is stored in a text file.
Secondary	A secondary zone is a read-only copy of the zone database. Changes cannot be made to the records in a secondary zone. A server that holds a secondary zone is called a secondary server. Secondary servers copy zone data from other servers through a process called zone transfer. Secondary servers can copy zone data from the primary server or other secondary servers. Zone data is stored in a text file.
Active Directory-integrated	An Active Directory-integrated zone holds zone data in Active Directory instead of a text file. Active Directory-integrated zones are multi-master zones, meaning that changes to the zone information can be made by multiple servers. Multiple servers hold read-write copies of the zone data. Only DNS servers that are domain controllers can host Active Directory-integrated zones. Storing zone data in Active Directory provides automatic replication, fault tolerance, and distributed administration of DNS data. Replication of zone data occurs during Active Directory replication and is secured by Kerberos.
Stub	A stub zone is a zone with only a partial copy of the zone database. The stub zone only contains information about the name servers that are authoritative for the zone; it does not contain information for other hosts. A stub zone is not authoritative for the zone; its purpose is to identify the name servers that can be contacted for full zone information. The stub zone is dynamic, meaning that it will keep the list of name servers for the zone updated automatically. Use a stub zone to forward name requests based on zones while keeping name server lists updated automatically.
GlobalNames	The GlobalNames zone is a special zone in the DNS database that is used for single-label name resolution. Use the GlobalNames zone to: Allow clients to use simple host names without domain information for name resolution. For example, to contact a server named web1.corp.us.westsim.private, users could simply enter the single-label name web1. Allow DNS clients to contact NetBIOS-only hosts without the need for a WINS server. Allow IPv6-only hosts to contact NetBIOS hosts (IPv6 does not support the use of WINS). Be aware of the following when using the GlobalNames zone: When users enter a single-label name, the client computer first tries to resolve the name using DNS and the search suffix configuration. If that process fails, the GlobalNames zone is checked (if it exists). Using the GlobalNames zone does not require any changes to client machines. Dynamic updates are not supported on the GlobalNames zone. You must manually create each record in the GlobalNames zone. Use the GlobalNames zone to replace WINS servers on your network only when you have a small number of hosts that do not support DNS. For a large number of NetBIOS-only hosts, or to support dynamic registration of single-label names, continue to use a WINS server.

 Source: Testout