The DNS database contains resource records (entries) that are used to resolve name resolution queries sent to the DNS server. Each DNS server contains the resource records it needs to respond to name resolution queries for the portion of the DNS namespace for which it is authoritative.
To add a resource record for a zone manually, right-click the zone icon in the DNS con-sole and from the shortcut menu, select the appropriate resource record you want to create.
To add a resource record for a zone manually, right-click the zone icon in the DNS con-sole and from the shortcut menu, select the appropriate resource record you want to create.
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.
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.
1. Resource Record Format
Resource records appear in varying formats, depending on the context in which they are used. For example, when lookups and responses are made using DNS, resource records are represented in binary form in packets. In the DNS console, resource records are represented graphically so that they can be viewed and modified easily. However, at the source—in the zone database files—resource records are represented as text entries. In fact, by creating resource records in the DNS console, you are automatically adding text entries to the corresponding zone’s database file.
In these zone files, resource records have the following syntax:
Owner TTL Class Type RDATA
Resource records appear in varying formats, depending on the context in which they are used. For example, when lookups and responses are made using DNS, resource records are represented in binary form in packets. In the DNS console, resource records are represented graphically so that they can be viewed and modified easily. However, at the source—in the zone database files—resource records are represented as text entries. In fact, by creating resource records in the DNS console, you are automatically adding text entries to the corresponding zone’s database file.
In these zone files, resource records have the following syntax:
Owner TTL Class Type RDATA
Most resource records are represented as single-line text entries. If an entry is going to span more than one line, parentheses can encapsulate the information. In many implementations of DNS, only the SOA resource record can contain multiple lines. For readability, blank lines and comments ignored by the DNS server are often inserted in the zone files. Comments always start with a semicolon (;) and end with a carriage return.
2. Record Types:
A few of the commonly used resource records (RR) and their associated functions are described . These are following:
1. Host (A) Resource Record
The host (A) resource record contains the IP address of a specific host, and maps the FQDN to this 32-bit IPv4 addresses. Host (A) resource records basically associates the domain names of computers (FQDNs) or hosts names to their associated IP addresses. Because a host (A) resource record statically associates a host name to a specific IP address, you can manually add these records to zones if you have machines who have statically assigned IP addresses.
The methods which are used to add host (A) resource records to zones are:
*Manually add these records, using the DNS management console.
*You can use the Dnscmd tool at the command line to add host (A) resource records.
A few of the commonly used resource records (RR) and their associated functions are described . These are following:
1. Host (A) Resource Record
The host (A) resource record contains the IP address of a specific host, and maps the FQDN to this 32-bit IPv4 addresses. Host (A) resource records basically associates the domain names of computers (FQDNs) or hosts names to their associated IP addresses. Because a host (A) resource record statically associates a host name to a specific IP address, you can manually add these records to zones if you have machines who have statically assigned IP addresses.
The methods which are used to add host (A) resource records to zones are:
*Manually add these records, using the DNS management console.
*You can use the Dnscmd tool at the command line to add host (A) resource records.
*TCP/IP client computers running Windows 2000, Windows XP or Windows Server 2003 use the DHCP Client service to both register their names, and update their host (A) resource records.
2. Alias (CNAME) Resource Record
Alias (CNAME) resource records ties an alias name to its associated domain name. Alias (CNAME) resource records are referred to as canonical names. By using canonical names, you can hide network information from the clients who connect to your network. Alias (CNAME) resource records should be used when you have to rename a host that is defined in a host (A) resource record in the identical zone.
3. Mail exchanger (MX) Resource Record
The mail exchanger (MX) resource record provides routing for messages to mail servers and backup servers. The mail MX resource record provides information on which mail servers processes e-mail for the particular domain name. E-mail applications therefore mostly utilize MX resource records.
A mail exchanger (MX) resource record has the following parameters:
*Priority
*Mail server
The mail exchanger (MX) resource record enables your DNS server to work with e-mail addresses where no specific mail server is defined. A DNS domain can have multiple MX records. MX resource records can therefore also be used to provide failover to different mail servers when the primary server specified is unavailable. In this case, a server preference value is added to indicate the priority of a server in the list. Lower server preference values specify higher preference.
4. Pointer (PTR) Resource Record
The pointer (PTR) resource record points to a different resource record, and is used for reverse lookups to point to A resource records. Reverse lookups resolve IP addresses to host names or FQDNs.
You can add PTR resource records to zones through the following methods:
*Manually add these records, using the DNS management console.
*You can use the Dnscmd tool at the command line to add PTR resource records.
5. Service (SRV) Resource Records
Service (SRV) resource records are typically used by Active directory to locate domain controllers, LDAP servers, and global catalog servers. The SRV records define the location of specific services in a domain. They associate the location of a service such as a domain controller or global catalog server; with details on how the particular service can be contacted.
The fields of the service (SRV) resource record are explained below:
*Service name
*The protocol used
*The domain name associated with the SRV records.
*The port number for the particular service
*The Time to Live value
*The class
*The priority and weight.
*The target specifying the FQDN of the particular host supporting the service
*Service name
*The protocol used
*The domain name associated with the SRV records.
*The port number for the particular service
*The Time to Live value
*The class
*The priority and weight.
*The target specifying the FQDN of the particular host supporting the service
6. Name Server (NS) Resource Record
The Name Server (NS) resource record provides a list of the authoritative DNS servers for a domain, as well authoritative DNS server for any delegated subdomains. Each zone must have one (or more) NS resource records at the zone root. The NS resource record indicates the primary and secondary DNS servers for the zone defined in the SOA resource record. This in turn enables other DNS servers to look up names in the domain.
7. Start of Authority (SOA) Resource Record
This is the first record in the DNS database file. The SOA record includes information on the zone property information, such as of the primary DNS server for the zone, and version information.
The fields located within the SOA record are listed below:
*Source host; the host for who the DNS database file is maintained
*Contact e-mail; e-mail address for the individual who is responsible for the database file.
*Serial number; the version number of the database.
*Refresh time; the time that a secondary DNS server waits, while determining whether database updates have been made, that have to be replicated via zone transfer.
*Retry time; the time for which a secondary DNS server waits before attempting a failed zone transfer again.
*Expiration time; the time for which a secondary DNS server will continue to attempt to download zone information. Old zone information is discarded when this limit is reached.
*Time to live; the time that the particular DNS server can cache resource records from the DNS database file.
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