The IP space chosen for the virtual network should not overlap any IP space used on-premises or in any other service used by your organization. For example, if your organization uses the 10.0.0.0/8 IP range on-premises, you would likely choose the 172.16.0.0/12 range in Azure to avoid any risk of overlap. Always consider that, even if you don’t want to connect Azure to your on-premises network today, you may want to connect in the future.
Separate IP address space between sub nets
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