CIDR format for IPs

Created by Abderrahim Ibnou el kadi, Modified on Fri, 11 Sep, 2020 at 8:33 AM by Jason Carreiro

Question

What is the CIDR format for Proofpoint Security Awareness Training IPs to allow whitelisting in Mimecast?

Answer

The CIDR format for our IPs:

52.202.140.133/32
54.173.248.25/32

Some whitelisting requires that the Subnet Mask of the IP be specified (especially if you're whitelisting a range of IPs vs an individual IP). CIDR is a way to express that subnet mask without writing out all of the octets of the address (such as 255.255.255.255). In this case /32 is designating an explicit IP address, not a range.

See Whitelisting Guide and Whitelisting in Mimecast for additional information.