The present invention discloses a method operable by a discovery system comprising at least one computerized device connected to an internet-protocol based network, the computerized device configured to operate a scan on a range of internet-protocol addresses and detect open ports available for communication. The discovery system is configured to generate an open port list denoted as first open port list of the open ports available for communication in the given range of the internet-protocol addresses and send request headers over an application protocol to at least one port of the ports in the first open port list and receive response headers comprising header fields from open ports available for communication in the range of internet-protocol addresses. The discovery system may be configured to utilize the header fields in a preconfigured data structure to identify device types, associate a test reference to the device type and preform the test accordingly to communicate with the identified open ports and determine vulnerability levels according to the test results.