IGMP has three versions. Different versions support different features. Which of the following features is supported by all versions?

The Membership Report message is a fundamental mechanism in all three versions of the Internet Group Management Protocol (IGMP). In IGMPv1, hosts send Membership Reports to declare interest in a multicast group. IGMPv2 enhanced the protocol but retained the core Report message. IGMPv3 further extended the Report message's capability to include source-specific information for Source-Specific Multicast (SSM), but the essential function of reporting group membership remains. Therefore, the Report message is the only feature listed that is common to IGMPv1, v2, and v3.

A. The Group-Specific Query message was introduced in IGMPv2 to allow a router to query for members of a specific group, a feature not present in IGMPv1.
B. The Leave message, which allows a host to explicitly signal its departure from a multicast group, was first introduced in IGMPv2.
D. Specifying a multicast source within a membership report is the primary feature of IGMPv3 and is not supported by IGMPv1 or IGMPv2.

1. Huawei HCIP-Datacom-Core Technology V1.0 Training Material: In the "IP Multicast Basics" section, the evolution of IGMP is detailed. It explicitly states that IGMPv1 defines only two types of messages: General Query and Membership Report. It then describes IGMPv2 adding the Leave Group and Group-Specific Query messages. Finally, it explains that IGMPv3's main enhancement is source filtering, which modifies the Membership Report to carry source addresses. This confirms the Report message is the common element. (Refer to HCIP-Datacom-Core Technology V1.0 Training Material, Chapter 4: IP Multicast Basics, Section: IGMP).

2. University Courseware (Stanford University): Lecture notes for networking courses often provide a comparative analysis of IGMP versions. For instance, Stanford's CS244a course materials detail the progression of IGMP, showing that Membership Reports are fundamental to v1, v2, and v3, while features like Leave messages and source specification are version-specific additions. (Refer to Stanford University, CS244a: An Introduction to Computer Networks, Lecture Notes on Multicast, Section: Internet Group Management Protocol (IGMP)).

3. IETF RFC 3376 (IGMPv3): This document, which defines IGMPv3, also provides a summary of the differences from previous versions. Section 2, "Comparison with IGMPv1 and IGMPv2," implicitly confirms that the Membership Report is a common feature, while highlighting that IGMPv2 added "Leave Group messages" and "Group-Specific Query messages," and IGMPv3 added "the ability for a system to report interest in receiving packets from specific source addresses." (Refer to RFC 3376, Section 2, Page 4).