Servad

Servad is a term used in computer networking to describe a service advertisement daemon, a background process responsible for announcing the availability of network services and enabling clients to discover them dynamically. A servad typically runs on hosts that provide services such as databases, web servers, or APIs, and it maintains a registry of active service instances.

Functionality includes collecting metadata (service name, version, protocol, port, health status), registering services with local or distributed registries, and advertising them to interested clients. Servads may support local multicast/broadcast discovery (DNS-SD/mDNS), as well as unicast discovery against a central registry. They handle renewal and expiry of advertisements and can respond to health-check queries or client requests for service details.

Architecture is modular: a servad runs as a lightweight daemon, with plugins for different transport methods and storage backends. It often supports security features such as access control lists, service authentication, and encrypted adverts to protect against spoofing.

Deployment contexts include microservices environments, containerized platforms, and IoT networks, where services shift as containers start and stop. In such settings, servads help reduce configuration drift by allowing clients to discover services automatically.

History and etymology: the term servad is used descriptively in various documentation as a concise label for a service advertisement daemon; there is no single standardized protocol named "servad." It is often implemented as part of larger service-discovery ecosystems or as a standalone utility.

Related concepts: service discovery, mDNS, DNS-SD, SSDP, Consul, etcd.