According to theFortiSwitchOS 7.6 Administration Guideand theFortiSwitch 7.6 Study Guide, Internet Group Management Protocol (IGMP) snooping is a Layer 2 mechanism that allows a switch to " listen " to IGMP conversations between hosts and routers to maintain a map of which ports require specific multicast streams. When IGMP snooping is enabled, the switch populates aMulticast Layer 2 Forwarding Table(as shown in the exhibit), which ensures that multicast traffic is only forwarded to ports where a receiver has explicitly requested it (e.g., PC1 on port1).

When IGMP snooping isdisabled, the switch no longer maintains this granular forwarding table. By default, a Layer 2 switch that is not performing IGMP snooping treats multicast traffic as if it werebroadcast traffic. Consequently, instead of being intelligently forwarded only to the interested receiver (PC1), the multicast traffic for group 225.1.2.3 will beflooded to all portswithin the same VLAN (VLAN 10). This means PC2, even if it has not joined the group, will receive the multicast packets at the physical layer, leading to unnecessary bandwidth consumption and increased CPU load on unintended recipients.

The documentation explicitly states that disabling IGMP snooping reverts the switch to a " flood-all " behavior for multicast frames within the broadcast domain. Option A is incorrect because the host (PC1) remains a member of the group; only the switch ' s forwarding logic changes. Option B is incorrect as the switch may still see the messages but will not act on them to prune ports. Option D is incorrect as disabling the feature removes the prune/stop mechanism, causing traffic to flow everywhere rather than stopping.