IPv4

The Internet Protocol (IP) address, is a unique number used to identify devices that are connected to a private network or the public internet. Today, the internet is largely based on version 4, IPv4. Kali includes several tools to facilitate DNS reconnaissance, as given in the following table:

During testing, most investigators run fierce to confirm that all possible targets have been identified, and then run at least two comprehensive tools (for example, dnsenum and dnsrecon) to generate the maximum amount of data and provide a degree of cross-validation.

In the following screenshot, dnsrecon is used to generate a standard DNS record search, and a search that is specific for SRV records. An excerpt of the results is shown for each case in the following screenshot:

DNSrecon allows the penetration tester to obtain the SOA record, name servers (NS), mail exchanger (MX) hosts, servers sending emails using Sender Policy Framework (SPF), and the IP address ranges in use.