Quickly Determining the Need for Sending Traffic to Subnet
Question
Which action enables an IPv6 multicast router on a subnet with locally attached receivers to quickly determine if there is a need to send traffic for a certain multicast group out to that subnet?
Answers
Explanations
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A. B. C. D.B.
The action that enables an IPv6 multicast router on a subnet with locally attached receivers to quickly determine if there is a need to send traffic for a certain multicast group out to that subnet is to adjust the MLD report interval on the router.
Multicast Listener Discovery (MLD) is the IPv6 equivalent of Internet Group Management Protocol (IGMP) for IPv4. It is used by IPv6 multicast routers to discover which hosts on a subnet are interested in receiving traffic for a specific multicast group.
When a host joins a multicast group, it sends an MLD report message to the local multicast router indicating its interest in receiving traffic for that group. The router maintains a list of the multicast groups that have at least one interested receiver on each of its attached subnets.
To quickly determine if there is a need to send traffic for a certain multicast group out to that subnet, the router can adjust the MLD report interval. By default, hosts send MLD report messages every 125 seconds. If the router receives an MLD report message from a host, it assumes that the host is still interested in the multicast group. If the router does not receive an MLD report message from a host within a certain period, it assumes that the host is no longer interested in the multicast group and can stop forwarding traffic for that group to that subnet.
By adjusting the MLD report interval, the router can reduce the time it takes to detect when there are no more interested receivers for a particular multicast group. This can help to conserve network bandwidth and resources.
Option B, activating IGPMv3 snooping and fast-leave, is not relevant to IPv6 multicast as IGPMv3 is used for IPv4 multicast. Option C, enabling the MLDv2 explicit-tracking feature, provides a way for the multicast router to track individual hosts' interest in a multicast group, but it is not necessary for the router to quickly determine if there is a need to send traffic for a certain multicast group out to that subnet. Option D, decreasing the ICMPv4 multicast query timer, is also not relevant to IPv6 multicast as it is used for IPv4 multicast.
