D adds a new Domain for DNSControl to manage. The first two arguments are required: the domain name (fully qualified example.com without a trailing dot), and the name of the registrar (as previously declared with NewRegistrar). Any number of additional arguments may be included to add DNS Providers with DNSProvider, add records with A, CNAME, and so forth, or add metadata.
Modifier arguments are processed according to type as follows:
  • A function argument will be called with the domain object as it's only argument. Most of the built-in modifier functions return such functions.
  • An object argument will be merged into the domain's metadata collection.
  • An array argument will have all of it's members evaluated recursively. This allows you to combine multiple common records or modifiers into a variable that can be used like a macro in multiple domains.
// simple domain
D("example.com", REG_MY_PROVIDER, DnsProvider(DSP_MY_PROVIDER),
CNAME("test", "foo.example2.com.")
// "macro" for records that can be mixed into any zone
MX("@", 1, "aspmx.l.google.com."),
MX("@", 5, "alt1.aspmx.l.google.com."),
MX("@", 5, "alt2.aspmx.l.google.com."),
MX("@", 10, "alt3.aspmx.l.google.com."),
MX("@", 10, "alt4.aspmx.l.google.com."),
D("example.com", REG_MY_PROVIDER, DnsProvider(DSP_MY_PROVIDER),
CNAME("test", "foo.example2.com."),

Split Horizon DNS

DNSControl supports Split Horizon DNS. Simply define the domain two or more times, each with their own unique parameters.
To differentiate the different domains, specify the domains as domain.tld!tag, such as example.com!inside and example.com!outside.
var REG_THIRDPARTY = NewRegistrar("ThirdParty");
var DNS_INSIDE = NewDnsProvider("Cloudflare");
var DNS_OUTSIDE = NewDnsProvider("bind");
D("example.com!inside", REG_THIRDPARTY, DnsProvider(DNS_INSIDE),
A("www", "")
D("example.com!outside", REG_THIRDPARTY, DnsProvider(DNS_OUTSIDE),
A("www", "")
A("internal", "")
A domain name without a ! is assigned a tag that is the empty string. For example, example.com and example.com! are equivalent. However, we strongly recommend against using the empty tag, as it risks creating confusion. In other words, if you have domain.tld and domain.tld!external you now require humans to remember that domain.tld is the external one. I mean... the internal one. You may have noticed this mistake, but will your coworkers? Will you in six months? You get the idea.
DNSControl command line flag --domains matches the full name (with the "!"). If you define domains example.com!george and example.com!john then:
  • --domains=example.com will not match either domain.
  • --domains='example.com!george' will match only match the first.
  • --domains='example.com!george",example.com!john will match both.
NOTE: The quotes are required if your shell treats ! as a special character, which is probably does. If you see an error that mentions event not found you probably forgot the quotes.