Computer networks is a complex subject due to the given reasons:
The first reason for the complexity of networks is that there are several different technologies exist for networking and each method features are differ from the other one. This is because many companies have discover networking standards, which are not compatible with other one. In this way multiple methods exist that are need to connect different networks.
The second reason for the complexity of networks is that there is no single relying model or theory, which defines or specifies different prospects of networking. Rather, several organizations and research groups have discovered conceptual models that may be used to illustrate similarities and differences between network software and hardware.
Another reason for the complexity of networks is that the conceptual models prepared by organization are either so simple that they do not distinguish between details, or they are so complex that they do not modify the subject.
One reason for the complexity of networks is that there is no uniform or simple method that can be used for the similar feature. Different methods use different terminologies.