Mac OS X, Mac OS X Server, Uncategorized

Managing DNS Services In macOS Server 5.4 for High Sierra

September 26, 2017

The changes in the Server app are pretty minimal in the macOS Server 5.4 version that we’re now looking at. All of the options from previous versions are still there and the dnsconfig command line interface for managing the service are basically unchanged. The DNS service in macOS Server, as with previous versions, is based on bind 9 (BIND 9.9.7-P3 to be exact). This is very much compatible with practically every DNS server in the world, including those hosted on Windows, macOS, Linux and even Zoe-R.

The first time you open the DNS Service click on the DNS service in the ADVANCED section of the list of SERVICES.

Then, click on the cog wheel icon below the list of records and click on Show All Records.

At the Records screen, you’ll now see forward and reverse record information. Click the Edit… button for the Forwarding Servers field. Here, you’ll be able to enter a Forwarders, or DNS servers that resolve names that the server you’re using can’t resolve using its own DNS records.

Click the plus sign to enter the IP address of any necessary Forwarders. Enter the IP address of any Forwarding servers, then click OK to save your changes.

Once back at the main DNS service control screen, click the Edit… button for Perform lookups for to configure what computers the DNS server you are setting up can use the DNS service that the server is hosting.

At the Perform Lookups screen, provide any additional subnets that should be used. If the server should be accessible by anyone anywhere, just set the “Perform lookups for” field at the DNS service screen to “all clients”.

All you have to do to start the DNS is click on the ON button (if it’s not already started, that is). There’s a chance that you won’t want all of the records that are by default entered into the service. But leave it for now, until we’ve covered what everything is. Next, click on the cog wheel icon below the records list, and you’ll see a list of all the records and record types that are currently running on the server.

To list the various types of records:

Then, when you click on the plus sign, you can create additional records. Double-clicking on records (including the Zones) brings up a screen to edit the record. The settings for a zone can be seen below.

These include the name for the zone. As you can see, a zone was created with the hostname rather than the actual domain name. This is a problem if you wish to have multiple records in your domain that point to the same host name. Theoretically you could create a zone and a machine record for each host in the domain, but the right way to do things is probably going to be to create a zone for the domain name instead of the host name. So for the above zone, the entry should be https://krypted.com/ rather than mavserver.krypted.com (the hostname of the computer). Additionally, the TTL (or Time To Live) can be configured, which is referenced here as the “Zone data is valid for” field. If you will be making a lot of changes this value should be as low as possible (the minimum value here is 5 minutes).

“Note: To make sure your zone name and TLD don’t conflict with data that already exists on the Internet, check here to make sure you’re not using a sponsored TLD.” — https://krypted.com//mac-os-x/dont-go-near-there-sponsored-top-level-domain-names/

Note: The above screen has the domain in the zone field and the name of a record, such as www for the zone called, for example, krypted.lan.

Click Done to commit the changes or create the new record.

Next, let’s create a MX record for the domain. To create the MX for the domain, click on the plus sign at the list of records.

Select the appropriate zone in the Zone field (if you have multiple zones). Then type the name of the A record that you will be pointing mail to. Most likely, this would be a machine record called simply mail, in this case for krypton.lan, so mail.krypted.lan. If you have multiple MX records, increment the priority number for the lower priority servers.

As a full example, let’s create a zone and some records from scratch. Let’s setup this zone for an Xsan metadata network, called krypted.xsan. Then, let’s create our metadata controller record as starbuck.krypted.xsan to point to 10.0.0.2 and our backup metadata controller record as apollo.krypted.xsan which points to 10.0.0.3. First, click on the plus sign and select Add Primary Zone.

At the zone screen, enter the name of the domain you’re setting up (e.g. krypted.com, also known as the zone), check the box for Allow zone transfers (there will be a second server) and click on the Done button. Click on the plus sign and then click on Add Machine record.

At the New Machine Record screen, select the appropriate zone as the Zone and then enter starbuck as the Host Name and click on the plus sign for IP Addresses and type in the appropriate IP. Click on Done to commit the changes. Repeat the process for each host that needs an address and then click Done to create the records.

Setting Up Secondary Servers

Now let’s setup a secondary server by leveraging a secondary zone running on a second computer. On the second macOS Server, click on the plus sign for the DNS service and select Add Secondary Zone.

https://krypted.com//?p=45195. In /private/var/named are a collection of each zone the server is configured for. Secondary zones are flat and don’t have a lot of data in them, but primary zones contain all the information in the Server app and the serveradmin outputs. To see the contents of our test zone we created, let’s view the /Library/Server/named/db.krypted.xsan file (each file name is db. followed by the name of the zone):

cat /var/named/db.krypted.xsan

https://krypted.com//mac-os-x-server/os-x-server-forcing-dns-propagation for information on forcing DNS propagation if you are having issues with zone transfers. Finally, you can manage all records within the DNS service using the new /Applications/Server.app/Contents/ServerRoot/System/Library/PrivateFrameworks/DNSManager.framework/dnsconfig command line tool. I’ve written an article on managing DNS using this tool, available here.

Setting Up Secondary Servers

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