Box 1: VM2, VM3 and VM4.
VM1 is in VNet1/Subnet1. VNet1 is peered with VNet2 and VNet3.
There are no NSGs blocking outbound ICMP from VNet1. There are no NSGs blocking inbound ICMP to VNet1/Subnet2, VNet2 or VNet3. Therefore, VM1 can ping VM2 in VNet1/Subnet2, VM3 in VNet2 and VM4 in VNet3.
Box 2:
VM4 is in VNet3. VNet3 is peered with VNet1 and VNet2. There are no NSGs blocking outbound ICMP from VNet3. There are no NSGs blocking inbound ICMP to VNet1/Subnet1, VNet1/Subnet2 or VNet2 from VNet3 (NSG10 blocks inbound ICMP from VNet4 but not from VNet3). Therefore, VM4 can ping VM1 in VNet1/
Subnet1, VM2 in VNet1/Subnet2 and VM3 in VNet2.
