The CLI excerpt is a static configuration. It only reveals which interfaces have IGMP enabled; it does not show the dynamic IGMP state table that records hosts that have actually sent joins. The presence, absence, or count of receivers for group 239.1.1.1 can only be verified with an operational command such as “show router igmp group-membership” (or PIM multicast routing table), not from configuration alone. Therefore the number of interfaces with receivers joined to 239.1.1.1 cannot be determined from the information provided.

A. One join could exist, but nothing in the config confirms it.

B. Two joins are equally unsubstantiated.

C. Three joins are equally unsubstantiated.

1. Nokia “7750 SR OS Multicast Protocols Guide”, 22.10.R1, Section 3.3.2 “IGMP Group Membership Table”, p. 109: configuration only enables IGMP; receiver joins appear in the operational table shown with “show router igmp group-membership”.

2. Nokia “SR OS Services Guide”, 22.10.R1, Chapter “IP Multicast Overview”, p. 51: “…the existence of an IGMP configuration on an interface does not imply the presence of an active host membership.”

3. C. Diot & G. Iannaccone, “Analysis of Multicast Routing Algorithms,” IEEE/ACM Trans. Networking, vol. 10 no. 4, 2002, Section II-A: distinguishes control-plane configuration from data-plane group membership learned dynamically.