imported>SirCharles: Reverting edit(s) by 5.209.216.232 (talk) to rev. 1209509237 by Greatpopcorn: Vandalism (RW 16.1)

2024-02-22T07:07:17Z

Reverting edit(s) by 5.209.216.232 (talk) to rev. 1209509237 by Greatpopcorn: Vandalism (RW 16.1)

New page

{{refimprove|date=September 2018}}
{{IPstack}}
{{short description|Protocol}}
The '''Link-Local Multicast Name Resolution''' ('''LLMNR''') is a protocol based on the [[Domain Name System]] (DNS) packet format that allows both [[IPv4]] and [[IPv6]] hosts to perform name resolution for hosts on the same local link. It is included in [[Windows Vista]], [[Windows Server 2008]], [[Windows 7]], [[Windows 8]], [[Windows 10]].<ref>[https://technet.microsoft.com/library/bb878128 LLMNR: The Cable Guy]</ref> It is also implemented by [[systemd]]-resolved on Linux.<ref>{{cite web |url=https://lwn.net/Articles/609740/ |title=systemd 216 available |accessdate=2015-08-10}}</ref> LLMNR is defined in RFC 4795 but was not adopted as an IETF standard.<ref>{{cite web|url=https://www.eiman.tv/blog/posts/lannames/#the-ietf-debacle|title=LLMNR, Multicast DNS and names on your LAN|author=Mikael Eiman|date=2015-05-25|accessdate=2021-01-30}}</ref>

As of April 2022, Microsoft has begun the process of phasing out both LLMNR and [[NetBIOS#Name service|NetBIOS]] name resolution in favour of [[Multicast DNS|mDNS]].<ref>[https://techcommunity.microsoft.com/t5/networking-blog/aligning-on-mdns-ramping-down-netbios-name-resolution-and-llmnr/ba-p/3290816 Aligning on mDNS: ramping down NetBIOS name resolution and LLMNR]</ref>

==Protocol details==
In responding to queries, responders listen on [[User Datagram Protocol|UDP]] port 5355 on the following link-scope [[Multicast address]]:
* IPv4 - 224.0.0.252, [[MAC address]] 01-00-5E-00-00-FC
* IPv6 - FF02:0:0:0:0:0:1:3 (this notation can be abbreviated as FF02::1:3), MAC address 33-33-00-01-00-03
The responders also listen on [[Transmission Control Protocol|TCP]] port 5355 on the [[unicast]] address that the host uses to respond to queries.

== Packet header structure ==
{| width="700" align="center"
|-
|
{| class="wikitable" style="margin: 0 auto; text-align: center;"
|- align="center"
! Bit offset
! colspan="4"| 0
! colspan="4"| 1
! colspan="4"| 2
! colspan="4"| 3
! colspan="4"| 4
! colspan="4"| 5
! colspan="4"| 6
! colspan="4"| 7
! colspan="4"| 8
! colspan="4"| 9
! colspan="4"| 10
! colspan="4"| 11
! colspan="4"| 12
! colspan="4"| 13
! colspan="4"| 14
! colspan="4"| 15
|- align="center"
! 0
| colspan="64"| ID
|- align="center"
! 16
! colspan="4"| QR
! colspan="16"| Opcode
! colspan="4"| C
! colspan="4"| TC
! colspan="4"| T
! colspan="4"| Z
! colspan="4"| Z
! colspan="4"| Z
! colspan="4"| Z
! colspan="16"| RCODE
|- align="center"
! 32
| colspan="64"| QDCOUNT
|- align="center"
! 48
| colspan="64"| ANCOUNT
|- align="center"
! 64
| colspan="64"| NSCOUNT
|- align="center"
! 80
| colspan="64"| ARCOUNT
|}
|}

* ID - A 16-bit identifier assigned by the program that generates any kind of query.
* QR - Query/Response.
* OPCODE - A 4-bit field that specifies the kind of query in this message. This value is set by the originator of a query and copied into the response. This specification defines the behavior of standard queries and responses (opcode value of zero). Future specifications may define the use of other opcodes with LLMNR.
* C - Conflict.
* TC - TrunCation.
* T - Tentative.
* Z - Reserved for future use.
* RCODE - Response code.
* QDCOUNT - An unsigned 16-bit integer specifying the number of entries in the question section.
* ANCOUNT - An unsigned 16-bit integer specifying the number of resource records in the answer section.
* NSCOUNT - An unsigned 16-bit integer specifying the number of name server resource records in the authority records section.
* ARCOUNT - An unsigned 16-bit integer specifying the number of resource records in the additional records section.

== See also ==
* Network Basic Input/Output System ([[NetBIOS]])
* [[Peer Name Resolution Protocol]] (PNRP)
* [[Multicast DNS]] (mDNS)
* [[Zero-configuration networking]] (Zeroconf)

== References ==
<references />

== External links ==
* [https://technet.microsoft.com/library/bb878128 Link-Local Multicast Name Resolution], Microsoft TechNet
* {{IETF RFC|4795|link=no}}, Informational, Link-Local Multicast Name Resolution (LLMNR)
* [https://www.eiman.tv/blog/posts/lannames/ LLMNR, Multicast DNS and names on your LAN]

[[Category:Internet protocols]]
[[Category:Domain Name System]]
[[Category:Application layer protocols]]
[[Category:Windows communication and services]]
[[Category:Windows Server]]
[[Category:Network protocols]]

Link-Local Multicast Name Resolution - Revision history

imported>SirCharles: Reverting edit(s) by 5.209.216.232 (talk) to rev. 1209509237 by Greatpopcorn: Vandalism (RW 16.1)