Slave DNSServer (app_Domain Name System) on Synology DS409slim

The Synology has DNS server software available from the Package Center. Let’s turn the NAS into a slave DNS server ; in case the primary virtual DNS server fails.

I’m running DSM 4.1-2668 on a Synology DS409slim.

Installing the DNS Server package

From the “Package Center”, select the “Available” tab. Scroll down until you see the “DNSServer beta” icon. Click “Install” and wait until it proceeds. When done, a “DNS Server” icon will appear in the “Installed” tab and the main menu. FYI, DNS Server Version 1.0-0012 ships with BIND v9.9.2.

From the “Installed” tab, click the “Run” button to start the “DNS Server” service. Having a look at the Syno’s console, you can see where the Bind daemon is installed and how it is launched.

# ps -w (...) 21604 nobody 11600 S /var/packages/DNSServer/target/bin/named -t /var/packages/DNSServer/target/named -u nobody (...)

What you see is that is it chrooted in “/var/packages/DNSServer/target/named” and runs as nobody.

Configuring DNS Server as a slave instance

From the main menu, click the “DNS Server” icon to start the management GUI.

From the “Zones” tab, click the “Create” button and choose “Slave Zone”. Select “Forward Zone” and the domain type and fill-in the “Domain name” and “Master DNS server”. You can check the “Limit source IP server” if you need to restrict DNS clients.
Dialog box to configure new DNS slave zone
When done, click “OK”.

Do the same for every slave zones you need to use.

From the “Resolution” tab, you’ll be able to configure forwarders and hosts that are allowed to do recursive queries on this DNS server.

Monitoring DNS Server

Use your local dig command to check if the resolver works. Then, add the DNS server to your monitoring tool.

Should you need to use “rndc stats“, this is how to use it, form the console:

# /var/packages/DNSServer/target/bin/rndc -k /var/packages/DNSServer/target/named/rndc.key stats # cat /var/packages/DNSServer/target/named/named.stats +++ Statistics Dump +++ (1361352472) ++ Incoming Requests ++ 1 QUERY ++ Incoming Queries ++ 1 MX ++ Outgoing Queries ++ [View: default] [View: _bind] ++ Name Server Statistics ++ 1 IPv4 requests received 1 responses sent 1 queries resulted in successful answer 1 queries resulted in authoritative answer ++ Zone Maintenance Statistics ++ 4 IPv4 notifies sent 4 IPv4 SOA queries sent 3 IPv4 AXFR requested 3 transfer requests succeeded (...)

The statistics format has changed (since 9.7?) and my graph tools are not ready for it (yet?). I’ll probably write about including Bind 9.7 in Xymon and getting pretty graphs some time.

Since then, That’s All Folks!

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