InformationLLMNR is a secondary name resolution protocol. With LLMNR, queries are sent using multicast over a local network link on a single subnet from a client computer to another client computer on the same subnet that also has LLMNR enabled. LLMNR does not require a DNS server or DNS client configuration, and provides name resolution in scenarios in which conventional DNS name resolution is not possible.
The recommended state for this setting is: Enabled.
An attacker can listen on a network for these LLMNR (UDP/5355) or NBT-NS (UDP/137) broadcasts and respond to them, tricking the host into thinking that it knows the location of the requested system.
Note: To completely mitigate local name resolution poisoning, in addition to this setting, the properties of each installed NIC should also be set to Disable NetBIOS over TCP/IP (on the WINS tab in the NIC properties). Unfortunately, there is no global setting to achieve this that automatically applies to all NICs - it is a per-NIC setting that varies with different NIC hardware installations.
SolutionTo establish the recommended configuration via GP, set the following UI path to Enabled:
Computer Configuration\Policies\Administrative Templates\Network\DNS Client\Turn off multicast name resolution
Note: This Group Policy path may not exist by default. It is provided by the Group Policy template DnsClient.admx/adml that is included with the Microsoft Windows 8.0 & Server 2012 (non-R2) Administrative Templates (or newer).
In the event DNS is unavailable a system will be unable to request it from other systems on the same subnet.
Disabled. (LLMNR will be enabled on all available network adapters.)