Can IP addresses of LANs that make up a WAN be the same?

Can IP addresses of LANs that make up a WAN be the same?

I would like to know whether the IP addresses for different physical locations (LANs) making up a WAN can be the same. For example, if a WAN comprises three locations, (A, B, and C) can the IP address in any two or all three locations be 216.62.86.100?

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The answer to your question is yes and no.

You can actually have as many locations as you want with the same IP addresses as long as they don't need to communicate between each other. If Location A needs to communicate with Location B or C, then you've got a problem; to be specific, it's what we call a "routing problem." Packets between networks won't be able to find their way to their correct destination because each location has the same addressing scheme.

Generally, when we design a network, we follow some guidelines and rules to ensure things will work with the least amount of possible problems. A fundamental rule in network design is to ensure we don't have overlapping networks, that is, each location must be unique and not overlap with another.

This was first published in October 2008