This question presupposes two things. The first is that you are familiar with networking and the systems and components it contains. The second is that your knowledge is sufficient to describe the different types of firewalls used within a network topology. As a technical support engineer, you are expected to know a broad range of computer systems, software, and technology. Since networks are a critical component of any organization's IT infrastructure, you need to be intimately familiar with the technology they employ and any issues that may occur and need to address. Suppose you don't already have this knowledge. In that case, it is highly recommended that you augment your expertise and experience by taking courses in networking, either online or at a certified training facility. Obtaining network certifications, such as those offered by Cisco, will further enhance your qualifications and ability to find a job.