Which type of device will detect but not prevent unauthorized access?

An intrusion detection system (IDS) will detect unauthorized access. However, it will not prevent unauthorized access. It is a form of audit control in a network. A firewall will protect your network from attack by placing rules on connections as to how people can connect as well as which traffic can pass. An intrusion protection system (IPS) will detect the presence of an intrusion and alert an administrator. A honeypot will attract a malicious user so their tactics can be observed. It performs this function by diverting the malicious user from production systems to the honeypot, which is a sacrificial system.