The Data Masking transformation masks an IP address as another IP address by splitting it into four numbers, separated by a period. The first number is the network. The Data Masking transformation masks the network number within the network range.
The Data Masking transformation masks a Class A IP address as a Class A IP Address and a 10.x.x.x address as a 10.x.x.x address. The Data Masking transformation does not mask the class and private network address. For example, the Data Masking transformation can mask 11.12.23.34 as 75.32.42.52. and 10.23.24.32 as 10.61.74.84.
When you mask many IP addresses, the Data Masking transformation can return nonunique values because it does not mask the class or private network of the IP addresses.