Private VLANs shouldn't be using public IP space, unless you own that IP space. You'll need to reconfigure your network, there's no way out of doing that.
Office365 portal IPs conflict with onprem DNS
Khurshid Alam - AC CESS
1
Reputation point
Dear Team We are trying to setup Hybrid Office 365 . But few IP ranges in Microsoftonline.com is same i our on prem. For example Microsoftonline is having ip range 20.x.x.x and in our onprem we have also 20.x.x.x subnet/vlan. So once we login it goes to our internal dns/core switch and does not resolve login.microsoftonline.com sites. Please advice how to get rid of this without changing our vlan.