||FreeBSD General Commands Manual
Multicast DNS (mDNS) & DNS Service Discovery (DNS-SD) Test
type domain port [key=value ...]
type domain port host IP [key=value
dns-sd command is a network diagnostic tool, much
However, unlike those tools, most of its functionality is not implemented in
dns-sd executable itself, but in library code that
is available to any application. The library API that
dns-sd uses is documented in
dns-sd command replaces the older mDNS command.
dns-sd command is primarily intended
for interactive use. Because its command-line arguments and output format
are subject to change, invoking it from a shell script will generally be
fragile. Additionally, the asynchronous nature of DNS Service Discovery does
not lend itself easily to script-oriented programming. For example, calls
like "browse" never complete; the action of performing a
"browse" sets in motion machinery to notify the client whenever
instances of that service type appear or disappear from the network. These
notifications continue to be delivered indefinitely, for minutes, hours, or
even days, as services come and go, until the client explicitly terminates
the call. This style of asynchronous interaction works best with
applications that are either multi-threaded, or use a main event-handling
loop to receive keystrokes, network data, and other asynchronous event
notifications as they happen.
If you wish to perform DNS Service Discovery operations from a scripting
language, then the best way to do this is not to execute the
dns-sd command and then attempt to decipher the
textual output, but instead to directly call the DNS-SD APIs using a binding
for your chosen language.
For example, if you are programming in Ruby, then you can directly call DNS-SD
APIs using the dnssd package documented at
Similar bindings for other languages are also in development.
To advertise the existence of LPR printing service on port 515 on this machine,
such that it will be discovered by the Mac OS X printing software and other
DNS-SD compatible printing clients, use:
- return a list of domains recommended for registering(advertising)
- return a list of domains recommended for browsing services.
Normally, on your home network, the only domain you are likely
to see is "local". However if your network administrator has
created Domain Enumeration records, then you may also see other
recommended domains for registering and browsing.
name type domain port [key=value
- register (advertise) a service in the specified
domain with the given name and
type as listening (on the current machine) on
name can be arbitrary unicode text,
containing any legal unicode characters (including dots, spaces,
slashes, colons, etc. without restriction), up to 63 UTF-8 bytes long.
type must be of the form
"_app-proto._tcp" or "_app-proto._udp", where
"app-proto" is an application protocol name registered at
domain is the domain in which to
register the service. In current implementations, only the local
multicast domain "local" is supported. In the future,
registering will be supported in any arbitrary domain that has a working
DNS Update server [RFC 2136]. The domain
"." is a synonym for "pick a sensible default" which
today means "local".
port is a number from 0 to 65535, and is
the TCP or UDP port number upon which the service is listening.
Additional attributes of the service may optionally be
described by key/value pairs, which are stored in the advertised
service's DNS TXT record. Allowable keys and values are listed with the
service registration at
- browse for instances of service type in
For valid types see
as described above. Omitting the domain or using
"." means "pick a sensible default."
name type domain
- look up and display the information necessary to contact and use the named
service: the hostname of the machine where that service is available, the
port number on which the service is listening, and (if present) TXT record
attributes describing properties of the service.
Note that in a typical application, browsing may only happen
rarely, while lookup (or "resolving") happens every time the
service is used. For example, a user browses the network to pick a
default printer fairly rarely, but once a default printer has been
picked, that named service is resolved to its current IP address and
port number every time the user presses Cmd-P to print.
name type domain port host IP
- create a proxy advertisement for a service running on(offered by) some
other machine. The two new options are Host, a name for the device and IP,
the address of it.
The service for which you create a proxy advertisement does
not necessarily have to be on your local network. You can set up a local
proxy for a website on the Internet.
name rrtype rrclass
- look up any DNS name, resource record type, and resource record class, not
necessarily DNS-SD names and record types. If rrtype is not specified, it
queries for the IPv4 address of the name, if rrclass is not specified, IN
class is assumed. If the name is not a fully qualified domain name, then
search domains may be appended.
- browse for service instances and display output in zone file format.
-G v4/v6/v4v6 name
- look up the IP address information of the name. If v4 is specified, the
IPv4 address of the name is looked up, if v6 is specified the IPv6 address
is looked up. If v4v6 is specified both the IPv4 and IPv6 address is
looked up. If the name is not a fully qualified domain name, then search
domains may be appended.
- return the version of the currently running daemon/system service.
-R "My Test" _printer._tcp. . 515
For this registration to be useful, you need to actually have LPR
service available on port 515. Advertising a service that does not exist is
not very useful, and will be confusing and annoying to other people on the
Similarly, to advertise a web page being served by an HTTP server
on port 80 on this machine, such that it will show up in the Bonjour list in
Safari and other DNS-SD compatible Web clients, use:
-R "My Test" _http._tcp . 80
To find the advertised web pages on the local network (the same
list that Safari shows), use:
While that command is running, in another window, try the
-R example given
above to advertise a web page, and you should see the "Add" event
reported to the
window. Now press Ctrl-C in the
-R window and you should see the "Remove"
event reported to the
In the example below, the www.apple.com web page is advertised as
a service called "apple", running on a target host called
apple.local, which resolves to 18.104.22.168.
-P apple _http._tcp "" 80 apple.local
The Bonjour menu in the Safari web browser will now show
"apple". The same IP address can be reached by entering
apple.local in the web browser. In either case, the request will be resolved
to the IP address and browser will show contents associated with
If a client wants to be notified of changes in server state, it
can initiate a query for the service's particular record and leave it
running. For example, to monitor the status of an iChat user you can
Everytime status of that user(someone) changes, you will see a new
TXT record result reported.
You can also query for a unicast name like www.apple.com and
monitor its status.
dns-sd bugs are tracked in Apple Radar component
dns-sd command first appeared in Mac OS X 10.4
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