ENC network has a fixed address range for encclient address assignment, defined by "startIP" and "endIP" parameters. That range can be reduced, but individual subranges cannot be excluded.
In a multitenant environment, where several IP ranges used by ENC can be in use, excluding subranges is needed. Changing the ENC range can be troublesome, as individual used subranges can lead to a very reduced ENC address range.
Think on an environment where these subranges are in use by "real" networks: 172.27.3.0/24 172.27.10.0/24 172.27.200.0/24 172.28.20.0/24 172.28.200.0/24
The biggest range that you could assign for ENC in that case would be 172.27.11.0 - 172.27.199.254, reducing the max number of encclients to 48000.
If IP range exclusion is added to ENC, ENC IP range definition could be something like this:
excludedIP: 172.27.3.0-172.27.3.255 172.27.10.0-172.27.10.255 172.27.200.0-172.27.200.255 172.28.20.0-172.28.20.255 172.28.200.0-172.28.200.255
This way, the total available IP addresses for ENC would be 127762, losing only 1270 IPs.