Following the recent acquisition of a new business, your manager asks you to investigate their DNS service and report back on its status. He is concerned as they only have one DNS server in the organization and it is visible on the Internet. What actions and recommendations should be taken as a first step?
The best course of action is to ensure zone transfer requests from the acquired business' DNS server are disabled, as unauthorized zone transfers can expose sensitive information. Additionally, proposing a plan to migrate the DNS service to a split-DNS infrastructure will enhance security by separating internal and external DNS traffic, which reduces the risk of exposing internal DNS information to potential threats on the internet.
It's B. By blocking 53 you would disable all DNS action (name resolvement and transfer) - this is not a solution. Best option is to disable unauthorised zone transfer and securly migrate DNS of new company to your infrastructure and split private and public DNS