Which IP addresses are considered RFC compliant for internal networks as required by 3CX?

RFC compliance for internal networks refers to the use of specific IP address ranges set aside for private use within organizations. The ranges defined in the relevant RFCs (specifically RFC 1918) are meant to ensure that internal IP addresses do not conflict with public IP addresses on the internet.

The IP address ranges that are designated for private networks include:

• 10.x.x.x: This range allows for a large number of hosts (over 16 million) within a single private network.

• 172.16.x.x to 172.31.x.x: This range provides 16 contiguous class B networks, accommodating over a million hosts.

• 192.168.x.x: This range is widely used for smaller networks and allows for up to 256 networks with 254 hosts each.

Since all these ranges comply with the RFC standards for private internal networks, they are valid choices for any organization running its internal network, including when setting up systems like 3CX. Therefore, the correct answer encompasses all of these options, affirming that any of these IP address ranges can be freely used for internal networking without the concern of overlapping with public IP addresses. Thus, the choice that includes all of these ranges is the most comprehensive and correct.