A method and system for monitoring and optimizing performance and availability of a Dynamic Host Configuration Protocol (DHCP) service provided by one or a plurality of DHCP servers (602) in an Internet Protocol (IP) network comprising one or a plurality of IP subnetworks. The method comprises in a DHCP server (602) defining one or a plurality of groups of subnetworks, a group of subnetworks comprising one or a plurality of subnetworks; retrieving information related to resources, in particular IP addresses, allocated within said DHCP server to each group of subnetworks; transferring said information to a DHCP service monitoring system (600). The method comprises in a DHCP service monitoring system (403) retrieving (501 to 505) from one or a plurality of DHCP servers (401), information related to resources, in particular IP addresses, allocated within each DHCP server (401) to groups of subnetworks, each group of subnetworks comprising one or a plurality of subnetworks and aggregating (506 to 511) the information for each group of subnetworks.