What would you consider the most effective perimeter and network defense methods available to safeguard network assets?

There are several methods that are used for maintenance of safety and defensing the network against any type of hacking or attacking.Some of the methods are mentioned as follows:-

Denial of service attack(Dos)-it is the type of service that does not let the unauthorized sources and users to use the resources of the service.Intrusion detection system(IDS)-it is the system that is used for the detection of any unauthorized access happening in the system.It detects the accessing on the basis of host and networkFirewall-is the system for the security of network for controlling the  traffic that enters and exits a networks and maintains barriers by blocking untrusted traffic.