"Companies depend on sales consultants to establish trust between clients and companies through their marketing, interpersonal, and customer service skills. Expect to draw heavily on previous experience during an interview. Popular questions ask about situations in which you have changed a client's mind or demonstrated strong interpersonal skills during challenging times. You may also have to demonstrate your sales skills by pitching a product to the interviewer."
The technical aspect of products and technology comparison, middleware, open source vs proprietary software and etc.
Knowledge on technology is required, and you need to have your own stance on why you choose technology A over technology B.