It does this by sending a 'ping' (hence the name, Freshping) to the server each minute and then recording (a) if there is a response and (b) how long it took the web server to respond.
Kwenza lokhu ngokuthumela i-'ping ' (yingakho igama, i-Freshping) kuseva umzuzu ngamunye bese kuqoshwa (a) uma kukhona impendulo futhi (b) kuthathe isikhathi esingakanani ukuthi iseva yewebhu iphendule.