In mobile phones, we have phone books. If we need to save someone's phone number, how we do that? Do we just enter the number and save it? No. We attach the number to a person's name or something we can remember, so the next time we open the contact list, we can easily find it. The same applies when you are dealing with IP addresses. I remember a few of the most commonly used IP addresses in my clients' infrastructure, but I do not remember most others. I remember lots of servers by their hostnames rather than their IP addresses. This is because hostnames are more user friendly and are easier to remember than IP addresses. This is exactly what DNS does: it maps IP addresses to domain names or common terms that are user friendly.
As I stated, there can be no functioning AD domain infrastructure without DNS. There are two main reasons why AD DS needs...