350-401 Practice Question: Consider the following configuration on a Cisco…

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✗

  The router will send IGMP membership reports for group 239.1.1.1 out of this interface.

  Why it's wrong here

  The static-group command (e.g., ip igmp static-group 239.1.1.1) creates a local IGMP group membership on the router, not a host behavior. IGMP membership reports are generated by end hosts in response to queries; the router interface remains a querier/forwarder, not a reporter. If the router sent reports out, it would falsely advertise itself as a receiver to a downstream querier, which is not the purpose. Instead, the command marks the interface as having a group member so the router updates its outgoing interface list accordingly, without generating any report traffic.

• ✓

  The router will include this interface in the outgoing interface list for group 239.1.1.1, even without any IGMP hosts.

  Why this is correct

  This command statically populates the IGMP group membership table for group 239.1.1.1 on this interface. As a result, the multicast routing process treats the interface as having a group member and adds it to the outgoing interface list (OIL) for that group in the multicast route entry. Even if no IGMP hosts ever send reports on this segment, multicast packets for the group are still forwarded out of the interface. This is a standard way to simulate a receiver for testing or to guarantee delivery to a network that lacks IGMP-capable hosts.

• ✗

  The router will drop all multicast traffic for group 239.1.1.1 on this interface.

  Why it's wrong here

  Static-group membership is an additive operation: it causes the interface to be included in the outgoing interface list for group 239.1.1.1, so multicast traffic is forwarded, not dropped. Dropping would require an explicit administrative boundary or filter, such as an ip multicast boundary or an interface-level ACL. Since the static-group command adds membership rather than imposing any filter, it cannot cause traffic to be discarded on that interface. The only effect is to include the interface in the OIL and thus forward the group's traffic.

• ✗

  The router will create a static multicast route for 239.1.1.1 via this interface.

  Why it's wrong here

  A static multicast route (mroute) is configured with the 'ip mroute' command and defines the reverse-path forwarding (RPF) neighbor or outgoing interface for a specific (S,G) pair. The ip igmp static-group command operates at the IGMP layer and only affects the group membership state on the interface; it does not alter the multicast routing table or RPF check. It determines which outgoing interfaces are placed in the OIL, but not the route or upstream neighbor used for forwarding. Therefore, it is incorrect to say this command creates a static multicast route.

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