PLESK 7.5 RELOADED > Performing Administrative Tasks

Managing DNS

Plesk provides administrators with an easy-to-use interface for managing the BIND domain name service it employs for serving domain names. Yet it automates the maintenance of DNS zones for the served domains: you configure a single DNS zone template, and when new domain names are created in Plesk, zone files for them are automatically generated in accordance with the template and are registered in the name server’s database. Thus, you will no longer have to bother with editing manually those multiple zone files and updating your name server startup configuration.

Automating creation of DNS zones server-wide

To have Plesk automatically generate zone files for the newly created domains and place them to the name server database, you are recommended to use a DNS zone template. By default the template includes all types of DNS records required to make the services of your domain available to the Internet users: NS records for specifying authoritative name servers for the zones, A records for resolving your server names into IP addresses, PTR records for serving reverse zones, which are required for reverse transformation of IP addresses to domain names, CNAME records for specifying the aliases to the canonical name, which are often used for defining types of Internet services running on you host (such as Web and FTP), and MX records for specifying mail exchange servers that are authorized to accept electronic mail coming to your domains. You have an option to include TXT records that can be used for implementing Sender Policy Framework anti-forgery solution to help your customers fight spammers. To learn about SPF, please refer to http://spf.pobox.com/index.html.

To view and manage the default template records, click the Server shortcut in the navigation pane and then click the DNS button under Services group. The DNS Template screen will open.

From this screen you can:

  1. Add and remove resource records to/from the template.

  2. Restore the original template configuration.

  3. Switch local DNS service off for the newly created domains. You would want to do this if you are running the domain name service on another host (other DNS servers are authoritative for the zones of hosted domain names).

  • To add a new resource record to the template, select a record type and click Add Record. Then specify the data appropriate for the selected resource record type. Note that you can use <ip> and <domain> templates that will be replaced in the generated zone with real IP addresses and domain names. You can use a wildcard to specify any part of the domain name. And of course, you can specify the exact values you need.

  • To remove a resource record from the template, in the list of records, select a corresponding check box, click Remove Selected, and then confirm removal.

  • To restore the original template configuration, click Default.

  • To turn off the local name service for the newly created domains, click the Disable button on the DNS template screen. After that, you will be able to validate zones on the authoritative DNS server against the hosting configuration of the domains served by Plesk in order to make sure that domain names and their services are properly resolved. This option is accessible from the Domain Administration screen, which is available for each domain (Domains > Domain name> DNS).

Configuring SOA record parameters

Start of Authority is a record in the zone file that marks the beginning of the zone. It has several parameters that you can customize manually via Plesk’s database:

  • SOA_TTL

  • SOA_Refresh

  • SOA_Retry

  • SOA_Expire

  • SOA_Minimum

The values of these parameters are stored in the "misc" table of "psa" database. If any of these parameter values are missing from the "misc" table, the default settings will be used. To set the new SOA record parameters, you need to insert the above parameters into the "misc" table with the new values.

Example:

# mysql -uadmin -p`cat /etc/psa/.psa.shadow` -D psa -e "INSERT INTO misc VALUES ('SOA_TTL','86400');"

If you have already set the SOA parameters, and need to change the current settings, you can do it using the commands like shown below:

# mysql -uadmin -p`cat /etc/psa/.psa.shadow` -D psa -e "UPDATE misc SET val='43200' WHERE param='SOA_TTL';"

Updated SOA parameters will be set for the newly created domains. If you need to update the SOA for an already existing domain, run the following command from shell:

/usr/local/psa/admin/sbin/dnsmng update domain.name.tld

Note: setting the TTL value to less than one hour can increase server load and produce unnecessary traffic.

Restricting Zone Transfers

By default DNS zone transfers are allowed only for the name servers designated by NS records contained within each zone. To allow DNS transfers server-wide on Plesk, click the Common ACL button on the DNS template screen.

A page will open displaying all hosts to which DNS zone transfers for all zones are allowed.

  • To add an entry, click the Add New Address button. Then specify the IP or network address and click OK.

  • To remove an entry from the access control list, select the corresponding checkbox and click Remove Selected.

Customizing DNS zone configuration for a specific domain

For each domain name, Plesk automatically creates a DNS zone in accordance with the DNS configuration presets that are changeable only by the server administrator. However, Plesk users allotted domain administration privileges can customize DNS zones for their own domains.

We would recommend modifying zones only to the users who have a good knowledge of DNS. Improper setup of DNS zone may result in improper functioning (or rather inaccessibility) of Web, mail, and FTP services.

If you use Plesk’s DNS service for serving the hosted domains, you may be interested in reading the sections “Adding and removing resource records to/from the zones” and “Changing zone type”. If you don’t, Plesk gives you the capabilities to validate zones on the authoritative DNS server against the hosting configuration of the domains served by Plesk. This is explained in the section “If your Plesk is not authoritative for the zone”.

To view and manage the zone for a specific domain, click the Domains shortcut in the navigation pane, select the domain name you need, and then click the DNS button under Services group.

The DNS zone properties screen will open.

From this screen you can:

  • Add/remove resource records to/from the zone, and restore the original zone configuration.

  • Change zone type.

  • Switch local DNS service off for a given domain. You should do this if another server is authoritative for your domain.

Adding and removing resource records to/from the zone

To add a new resource record to the zone, select a record type and click Add. Then you will need to specify the data appropriate for the selected resource record type:

  • For an A record you will need to enter the domain name for which you wish to create an A record. If you are simply defining an A record for your main domain, then you should leave the available field empty. If you are defining an A record for a name server then you will need to input the appropriate entry for the given name server (ie. ns1). Then, you need to enter the appropriate IP address to which to associate the domain name.

  • For a NS record, you will need to enter the domain name for which you wish to create the NS record. If you are defining an NS record for your main domain, then you will leave the available field blank. Then enter the appropriate name server name in the field provided. You will need to enter the complete name (i.e. ns1.mynameserver.com).

  • For a MX record, you will need to enter the domain for which you are creating the MX record. For the main domain, you would simply leave the available field blank. You will then need to enter your mail exchanger, this is the name of the mail server. If you are running a remote mail server named 'mail.myhostname.com' then you would simply enter 'mail.myhostname.com' into the field provided. You will then need to set the priority for the mail exchanger. Select the priority using the drop-down box: 0 is the highest and 50 is the lowest. Keep in mind you would also need to add the appropriate A record, and/or CNAME if applicable for the remote mail exchange server.

  • For a CNAME record, you will need to first enter the alias domain name for which you wish to create the CNAME record. You then need to enter the domain name within which you want the alias to reside. Any domain name can be entered. It does not need to reside on the same server.

  • For a PTR record you will first enter the IP address/mask for which you wish to define the pointer. Then enter the appropriate domain name for this IP to be translated to.

  • For a TXT record, you will be able to enter an arbitrary text string, which could be a description or an SPF record.

  • Click OK to submit the data.

To remove a resource record from the zone, in the list of resource records, select a corresponding check box, click Remove Selected, and then confirm removal.

To restore the original zone configuration by the DNS template, in the IP address drop-down box, select the IP address to be used with a template, specify whether a WWW alias is required for the domain, and click the Default button.

Changing zone type

You can specify whether Plesk’s DNS server should act as a master or slave name server when serving a zone. A DNS master server stores locally the zone file it serves, while a slave server only retrieves a copy of this file from the master.

By default, when a new domain name is created, the Plesk’s domain name server is instructed to act a master for this zone. If you have another machine serving this zone as a master, and wish to make this Plesk server act as slave, you should switch the zone type to slave.

To switch the zone type from master to slave:

  1. At the zone properties screen (Domains > Domain name> DNS) click Switch icon. The DNS Zone Properties page will open and the DNS zone type will change to slave.

  2. Specify the IP address of the master DNS server.

  3. Click Add.

To make the Plesk’s DNS server act a master for this zone, at the zone properties screen (Domains > Domain name> DNS) click Switch icon. The appropriate resource records for the zone will be restored as they were retained before you switched the zone type.

If your Plesk server is not authoritative for a zone

You should switch off the control panel’s DNS service for each individual zone served by external name servers. To do this, at the zone properties screen (Domains > Domain name> DNS), click the Disable icon. Turning the DNS service off for the zone will refresh the screen, so that only a list of name servers remains.

Note

The listed NS records have no effect on the system. They are only presented as clickable links on the screen to give you a chance to validate the configuration of the zone maintained on the external authoritative name servers through the control panel.

If you wish to validate the configuration of the zone maintained on the authoritative name servers:

  1. Add to the list the entries pointing to the appropriate name servers that are authoritative for the zone: click Add, specify a name server, and click OK. Repeat this for each name server you would like to test. The records will appear in the list.

  2. Click on the records that you just created. Plesk will retrieve the zone file from a remote name server, and check the resource records to make sure that domain’s resources are properly resolved. The results are interpreted and displayed on the screen.


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