DNS Enumeration
DNS enumeration is the process of locating all the DNS servers and their corresponding records for an organization. DNS enumeration will yield usernames, computer names, and IP addresses of potential target systems. The list of DNS record provides an overview of types of resource records (database records) stored in the zone files of the Domain Name System (DNS). The DNS implements a distributed, hierarchical, and redundant database for information associated with Internet domain names and addresses.
DNS Zone Transfer used to replicate DNS data across a number of DNS servers or to back up DNS files. A user or server will perform a specific zone transfer request from a ―name server. If the name server allows zone transfers by an anonymous user to occur, all the DNS names and IP addresses hosted by the name server will be returned in human-readable ASCII text.
Tools:
nslookup, maltego, dnenum,dnsrecon
Countermeasures:
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Disable Zone transfer by untrusted hosts
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Ensure that private hostnames are not referenced to IP addresses within the DNS zone files of publicly accessible DNS servers.
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Use premium registration services.