Depends on what part you're referring to. There are "boots" on the rack and pinion steering gear and there are boots on the inner and outer cv joints. All of them keep dirt and water out. The cv joint boots keep the grease in. Have the car inspected at a different shop at your convenience, but don't tell them specific things to look for. Just let them find things on their own, then compare their findings to those of the previous shop. When they find that split boot, ask for an opinion as to the cause. Your vehicle is too new to have dry-rotted parts. Hard rubber parts often split at sharp creases. Soft rubber parts tend to get cut near the bands that clamp them in place.