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LLMNR
Link-Local Multicast Name Resolution (LLMNR) is a protocol that enables devices on the same local network segment to perform name resolution without requiring a DNS server. Primarily found in Microsoft environments starting from Windows Vista and Server 2008, LLMNR facilitates communication during network initialization or when DNS is unavailable..
Overview:
Link-Local Multicast Name Resolution (LLMNR) is a protocol designed to provide name resolution on hosts connected to the same local subnet without relying on external DNS servers. It functions by sending multicast queries to specific IPv4 and IPv6 multicast addresses, enabling devices to resolve each other's names.
Protocol Details:
LLMNR operates over both TCP and UDP on port 5355. It uses multicast address 224.0.0.252 (IPv4) or FF02::1:3 (IPv6) to transmit queries to all local hosts. If a device recognizes the queried name as its own, it responds directly to the querying host. Thus, LLMNR supports peer-to-peer name resolution in small, unmanaged or transient networking environments.
Deployment Context:
LLMNR is enabled by default on many Windows-based systems, especially within workgroup settings without centralized DNS infrastructure. It can assist during network bootstrapping or for temporary ad-hoc communications. However, in managed or enterprise environments, proper DNS use is preferred, and LLMNR is often disabled for security reasons.