root@kali:~# fierce -h usage: fierce [-h] [--domain DOMAIN] [--connect] [--wide] [--traverse TRAVERSE] [--search SEARCH [SEARCH ...]] [--range RANGE] [--delay DELAY] [--subdomains SUBDOMAINS [SUBDOMAINS ...] | --subdomain-file SUBDOMAIN_FILE] [--dns-servers DNS_SERVERS [DNS_SERVERS ...] | --dns-file DNS_FILE] [--tcp] A DNS reconnaissance tool for locating non-contiguous IP space. options: -h, --help show this help message and exit --domain DOMAIN domain name to test --connect attempt HTTP connection to non-RFC 1918 hosts --wide scan entire class c of discovered records --traverse TRAVERSE scan IPs near discovered records, this won't enter adjacent class c's --search SEARCH [SEARCH ...] filter on these domains when expanding lookup --range RANGE scan an internal IP range, use cidr notation --delay DELAY time to wait between lookups --subdomains SUBDOMAINS [SUBDOMAINS ...] use these subdomains --subdomain-file SUBDOMAIN_FILE use subdomains specified in this file (one per line) --dns-servers DNS_SERVERS [DNS_SERVERS ...] use these dns servers for reverse lookups --dns-file DNS_FILE use dns servers specified in this file for reverse lookups (one per line) --tcp use TCP instead of UDP