dns-sd(1)						    BSD General Commands Manual 						 dns-sd(1)

NAME

     dns-sd -- Multicast DNS (mDNS) & DNS Service Discovery (DNS-SD) Test Tool

SYNOPSIS

     dns-sd -E

     dns-sd -F

     dns-sd -R name type domain port [key=value ...]

     dns-sd -B type domain

     dns-sd -L name type domain

     dns-sd -P name type domain port host IP [key=value ...]

     dns-sd -q name rrtype rrclass

     dns-sd -Z type domain

     dns-sd -G v4/v6/v4v6 name

     dns-sd -V

DESCRIPTION

     The dns-sd command is a network diagnostic tool, much like ping(8) or traceroute(8).  However, unlike those tools, most of its functionality
     is not implemented in the dns-sd executable itself, but in library code that is available to any application.  The library API that dns-sd
     uses is documented in /usr/include/dns_sd.h.  The dns-sd command replaces the older mDNS command.

     The 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 con-
     tinue 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 lan-
     guage.
     For example, if you are programming in Ruby, then you can directly call DNS-SD APIs using the dnssd package documented at
     <http://rubyforge.org/projects/dnssd/>.
     Similar bindings for other languages are also in development.

     dns-sd -E
	return a list of domains recommended for registering(advertising) services.

     dns-sd -F
	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.

     dns-sd -R 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 port.

	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 appli-
	cation protocol name registered at http://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xml.

	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
	http://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xml.

     dns-sd -B type domain
	browse for instances of service type in domain.

	For valid types see http://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xml.	as described above. Omit-
	ting the domain or using "." means "pick a sensible default."

     dns-sd -L 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.

     dns-sd -P name type domain port host IP [key=value ...]
	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.

     dns-sd -q 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 qual-
	ified domain name, then search domains may be appended.

     dns-sd -Z type domain
	browse for service instances and display output in zone file format.

     dns-sd -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.

     dns-sd -V
	return the version of the currently running daemon/system service.

EXAMPLES

     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:

	   dns-sd -R "My Test" _printer._tcp. . 515 pdl=application/postscript

     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 network.

     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:

	   dns-sd -R "My Test" _http._tcp . 80 path=/path-to-page.html

     To find the advertised web pages on the local network (the same list that Safari shows), use:

	   dns-sd -B _http._tcp

     While that command is running, in another window, try the dns-sd -R example given above to advertise a web page, and you should see the "Add"
     event reported to the dns-sd -B window. Now press Ctrl-C in the dns-sd -R window and you should see the "Remove" event reported to the dns-sd
     -B window.

     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 17.149.160.49.

	   dns-sd -P apple _http._tcp "" 80 apple.local 17.149.160.49

     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 www.apple.com.

     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 run-
     ning.  For example, to monitor the status of an iChat user you can use:

	   dns-sd -q someone@ex1._presence._tcp.local txt

     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 -q www.apple.com

FILES

     /usr/bin/dns-sd

SEE ALSO

     mDNSResponder(8)

BUGS

     dns-sd bugs are tracked in Apple Radar component "mDNSResponder".

HISTORY

     The dns-sd command first appeared in Mac OS X 10.4 (Tiger).

Darwin								   May 31, 2019 							    Darwin