D. J. Bernstein

Internet publication

DNScache

Frequently asked questions

DNS server

How do I configure a DNS server? I'm in charge of the heaven.af.mil and 1.2.3 networks. I'd like to run tinydns on IP address 1.2.3.5 to publish my host addresses through DNS.

Answer: This answer assumes that your boot scripts are already running svscan in a /service directory. tinydns relies on svscan to start it and to restart it at boot time.

You will have to make three decisions:

Create the service directory by running the tinydns-conf program, with your IP address at the end of the line: 
     /usr/local/dnscache/bin/tinydns-conf tinydns dnslog /etc/tinydns 1.2.3.5
Tell svscan about the new service: 
     ln -s /etc/tinydns /service
svscan will start the service within one minute.

Now tell tinydns to answer questions about the heaven.af.mil and 3.2.1.in-addr.arpa domains, and to advertise 1.2.3.5 as the DNS server address for each domain: 

     cd /service/tinydns/root
     ./add-ns heaven.af.mil 1.2.3.5
     ./add-ns 3.2.1.in-addr.arpa 1.2.3.5
     make
You can also add host addresses and mail-server addresses, as described below.

Finally, tell the administrator of af.mil to delegate heaven.af.mil to the server a.ns.heaven.af.mil running on IP address 1.2.3.5. Similarly, tell the administrator of 2.1.in-addr.arpa to delegate 3.2.1.in-addr.arpa to the server a.ns.3.2.1.in-addr.arpa running on IP address 1.2.3.5.

How do I tell tinydns about a host address? I have three computers: lion on IP address 1.2.3.4, tiger on IP address 1.2.3.5, and bear on IP address 1.2.3.6.

Answer: 

     cd /service/tinydns/root
     ./add-host lion.heaven.af.mil 1.2.3.4
     ./add-host tiger.heaven.af.mil 1.2.3.5
     ./add-host bear.heaven.af.mil 1.2.3.6
     make
The ./add-host scripts edit the file /service/tinydns/root/data, which is in tinydns-data format. make runs the tinydns-data program to tell tinydns about the new information. If anything goes wrong, tinydns-data prints an error message, and tinydns continues providing the old information.

As an alternative to ./add-host, you can edit data manually, adding the following lines: 

     =lion.heaven.af.mil:1.2.3.4
     =tiger.heaven.af.mil:1.2.3.5
     =bear.heaven.af.mil:1.2.3.6
But the ./add-host scripts will prevent you from accidentally reusing a previous host name, or reusing a previous IP address. They're also very careful in how they write the new file to disk, so nothing can go wrong if there's a sudden power outage.
How do I tell tinydns about a mail server address? I've set up an MTA on IP address 1.2.3.4 to handle incoming mail for heaven.af.mil.

Answer: 

     cd /service/tinydns/root
     ./add-mx heaven.af.mil 1.2.3.4
     make
(mx stands for ``mail exchanger.'') As an alternative to add-mx, you can edit data manually, adding the following line: 
     @heaven.af.mil:1.2.3.4:a
If you add several mail servers for heaven.af.mil, use a for the first, b for the second, etc. add-mx handles this automatically.
How do I replicate my DNS service? Right now IP address 1.2.3.5 is handling all heaven.af.mil queries and 3.2.1.in-addr.arpa queries. I'd like to provide identical information from another machine on IP address 1.2.3.6, so that DNS queries are answered even if one machine crashes.

Answer: First, use tinydns-conf to configure tinydns on 1.2.3.6: 

     /usr/local/dnscache/bin/tinydns-conf tinydns dnslog /etc/tinydns 1.2.3.6
     ln -s /etc/tinydns /service

Next, add your favorite file-management tools to /service/tinydns/root/Makefile on 1.2.3.5 so that changes in /service/tinydns/root/data are automatically copied to 1.2.3.6.

Now tell tinydns about the new server: 

     cd /service/tinydns/root
     ./add-ns heaven.af.mil 1.2.3.6
     ./add-ns 3.2.1.in-addr.arpa 1.2.3.6
     make

Finally, tell the administrator of af.mil to add a delegation of heaven.af.mil to the server b.ns.heaven.af.mil running on IP address 1.2.3.6. Similarly, tell the administrator of 2.1.in-addr.arpa to add a delegation of 3.2.1.in-addr.arpa to the server b.ns.3.2.1.in-addr.arpa running on IP address 1.2.3.6.

How do I delegate a domain to another server? I'd like to delegate the elysium.heaven.af.mil domain to IP address 1.2.3.144.

Answer: 

     cd /service/tinydns/root
     ./add-childns elysium.heaven.af.mil 1.2.3.144
     make
As an alternative to add-childns, you can edit data manually, adding the following line: 
     &elysium.heaven.af.mil:1.2.3.144:a
If you delegate heaven.af.mil to several IP addresses, use a for the first, b for the second, etc. add-childns handles this automatically.