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# dnssd

Discover, publish, and resolve network services on a local area or wide area network.

## Overview

The DNS Service Discovery API helps you to perform three main tasks:

- Registering a service.
- Browsing for services.
- Resolving service names to host names.

In support of these main tasks, this API can directly assist you in performing two subsidiary tasks:

- Enumerating domains (finding recommended service domains).
- Updating registrations (changing your DNS registration data dynamically).

Most apps shouldn’t use this API, and instead should use a higher-level service discovery API like <doc://com.apple.documentation/documentation/Foundation/NetService>. Use dnssd if you’re writing BSD-style applications or cross-platform programs that don’t need to link to higher-level frameworks. You can also use dnssd if you need specific lower-level functionality exposed by this API.

> Important:
> Apps that use the local network must provide a usage string in their `Info.plist` file with the key <doc://com.apple.documentation/documentation/BundleResources/Information-Property-List/NSLocalNetworkUsageDescription>. Apps that use <doc://com.apple.documentation/documentation/Foundation/bonjour> must also declare the services they browse, using the <doc://com.apple.documentation/documentation/BundleResources/Information-Property-List/NSBonjourServices> key.

## Topics

### Reference

[DNS Service Discovery C](/documentation/dnssd/dns-service-discovery-c)

See the Overview section above for header-level documentation.

[dnssd Enumerations](/documentation/dnssd/dnssd-enumerations)

[dnssd Functions](/documentation/dnssd/dnssd-functions)

[dnssd Data Types](/documentation/dnssd/dnssd-data-types)

[dnssd Constants](/documentation/dnssd/dnssd-constants)


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