NA Lesson - 24

Deploying DNS Servers (Part-3)

DNS Resource Records

To add a resource record to a zone, complete the following steps:

1. Open the DNS console.

2. In the console tree, right-click the applicable zone and select Other New Records. The Resource Record Type dialog box appears.

3. In the Select A Resource Record Type list box, select the type of resource record you want to add.

4. Click Create Record.

5. In the New Resource Record dialog box, enter the information needed to complete the resource record.

6. After you specify all of the necessary information for the resource record, click OK to add the new record to the zone.

7. Click Done to return to the DNS console.

Resource Record Types

■ Host (A)

■ Alias (CNAME)

■ Mail exchanger (MX)

■ Pointer (PTR)

■ Service location (SRV)

Host (A) Resource Records

Host (A) resource records make up the majority of resource records in a zone database. These records are used in a zone to associate DNS domain names of computers (or hosts) to their IP addresses.

Alias (CNAME) Resource Records

Alias (CNAME) resource records are also sometimes called canonical names. These records allow you to use more than one name to point to a single host. For example, the well-known server names (ftp, www) are typically registered using CNAME resource records. These records map the host name specific to a given service (such as ftp.lucernepublishing.com) to the actual A resource record of the computer hosting the service (such as server-boston.lucernepublishing.com).

MX Resource Records

The mail exchanger (MX) resource record is used by e-mail applications to locate a mail server within a zone. It allows a domain name such as lucernepublishing.com, specified in an e-mail address such as joe@lucernepublishing.com, to be mapped to the A resource record of a computer hosting the mail server for the domain. This type of record thus allows a DNS server to handle e-mail addresses in which no particular mail server is specified.

PTR Resource Records

The pointer (PTR) resource record is used only in reverse lookup zones to support reverse lookups, which perform queries to resolve IP addresses to host names or FQDNs. Reverse lookups are performed in zones rooted in the in-addr.arpa domain. PTR resource records are added to zones by the same manual and automatic methods used to add A resource records.

SRV Resource Records

Service location (SRV) resource records are used to specify the location of specific services in a domain. Client applications that are SRV-aware can use DNS to retrieve the SRV resource records for given application servers.

Windows Server 2003 Active Directory is an example of an SRV-aware application. The Netlogon service uses SRV records to locate domain controllers in a domain by searching the domain for the Lightweight Directory Access Protocol (LDAP) service.

Q. Discuss various types of DNS Resource Records.