• Static threshold set for the subnet <range name> has been reached.
• Dynamic threshold set for the subnet <range name> has been reached.
• Static threshold set for the subnet <range name> has been reached.
• The threshold set for the super scope <super scope name> on server <server name> has been reached

This warning is shown when a specific threshold is reached, that is, not enough IP addresses is available in this range. To fix this issue remove the scope and create a larger one instead or create a super scope which will join together two or more scopes for larger one.