DNS cache locking

- [Instructor] Since DNS is such a critical network service,…it's important that you try to protect it…as much as possible.…Now one way that we can help protect DNS is through…the use of something called DNS cache locking.…DNS cache locking is a security feature…that you can use to control when information…in the DNS cache can be overwritten.…So we've already learned that when a recursive DNS server…responds to a query, that server will cache the results…so that it can respond quickly if it happens to get…another query looking for the same information.…

The amount of time that the DNS server will hold on…to that information in the cache is determine by something…called the TTL or the time to live value.…So here's the deal, the way it's been set up is…that it's possible for that information in the cache…to be updated if there's more recent information…than when it was first put into the cache,…but like with many other features, we end up having…malicious users who ruin it for the rest of us.…So what the malicious users will do is they will go ahead…