"Deciding on what hardware to use in a computer network topology begins with staying current on the technology available. I make sure to take time to understand the different pieces of hardware developed by our vendors and which will fit into our network designs. Once I've created the basic network layout, I then select pieces of hardware which will ensure the network performs effectively and efficiently and meet the budget requirements for the project. I collaborate with other network architects and project stakeholders to discuss the merits of each option and make the final determination of what equipment we will use. I also rely heavily on the vendor's recommendations and input from their technical staff."

What they're looking for in your answer is a description of how you maintain your knowledge of current technology, specify several alternatives for each piece of hardware, and select the one that's most appropriate for the design you architected. Since this is an operational question about how you do your job, you should keep your answer brief and to the point and anticipate follow-up questions from the interviewer.