As a Certified Ethical Hacker, you are conducting a footprinting and reconnaissance operation against a target organization. You discover a range of IP addresses associated with the target using the…

The `-t axfr` option attempts an AXFR (zone transfer), which is generally used for enumerating all records for a *known domain* and is rarely successful for external reconnaissance, rather than performing reverse lookups on an IP range to discover domains and their NS/MX records.

The `-t zonewalk` option is used for DNS zone walking, which enumerates records within a *specific domain* (often via NSEC records), and is not the appropriate method for iterating through an IP range to perform reverse lookups.

The `dnsrecon -r 162.241.216.0/24 -t std` command is the most effective because the `-r` flag is used to specify an IP range for reverse DNS lookups (PTR records), and the `-t std` (standard enumeration) type ensures that after discovering domain names from these PTR records, `dnsrecon` will also query for NS (nameserver) and MX (mail exchange) records for those discovered domains, fulfilling all aspects of the question.

The `-d example.com` flag specifies a target *domain* for forward enumeration, which contradicts the goal of *discovering* domain names through reverse lookups on an IP range, and the `-t brt` (brute-force) option is primarily for finding subdomains of a known domain, not for reverse DNS lookups.