Subject: Multicast and DNS

From: "Joel Martin" <[email-masked]>
Date: Wed, 9 Jul 1997 10:19:01 +0000

Can you tell me what role the Domain Name Servers play in 
Multicasting? How are all the destinations for a Multicast Group
retrieved from DNS prior to sending to the "appropriate" Multicast
enabled routers?

Thanks for your help.

Joel

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From: Yong Xue <[email-masked]>
Date: Thu, 10 Jul 1997 07:18:15 -0400

>retrieved from DNS prior to sending to the "appropriate" Multicast

Joel,

Multicast works differently than unicast. Multicast traffic source sends
packets to a group address, NOT a list of individual ip addresses. Hosts
can join and leave a group dynamically. Multicast routers run multicast
routing protocol and group management protocol (IGMP) to learn the group
member distribution info and network topology, thereby constructing an
optimal multicast distribution tree to deliver a multicast packet to all
the group remember on the network. This distribution tree also changes with
the group membership status.