Comprehensive and Detailed Step-by-Step Explanation:
1. Understanding the IGMP Group Entry:
The IGMP group entry contains key information about multicast groups on the interface:
* Group Address (225.1.1.2): The multicast group address that the user has joined.
* Last Reporter (10.1.6.10): The IP address of the last host that sent an IGMP Report message for this group.
* Uptime: The duration since the group was first reported.
* Expires: The remaining time before the group entry ages out if no further reports are received.
2. Analysis of Each Statement:
Option A: This entry can be used to construct the corresponding (S, G) entry.
* Incorrect.
* This is a group entry for IGMP, which contains information about the group (G) but does not include a specific source (S). (S, G) entries are created in PIM (Protocol Independent Multicast), not IGMP.
Option B: This entry is created when the device receives an IGMP Join message from a user.
* Correct.
* IGMP Join messages are used by hosts to signal their intent to join a multicast group. When such a message is received, the group entry is created.
Option C: Expires indicates the aging time of the IGMP group.
* Correct.
* The "Expires" field shows the remaining time before the group entry ages out if no further IGMP reports are received.
Option D: 225.1.1.2 is the address of the group that the user joins.
* Correct.
* The "Group Address" field explicitly states that 225.1.1.2 is the multicast group that the user has joined.
3. Summary:
* Correct Options: B, C, D