Which footprinting method helps identify the ports and services a web server runs?

Which footprinting method helps identify the ports and services a web server runs?

• A. Banner grabbing
• B. Service discovery
• C. DNS zone transfer
• D. DNS enumeration

Answer: (B)

Service discovery is about mapping a host’s open ports to the services running on them. It usually starts with scanning to see which ports are open, then identifying what service is listening on each port (for a web server, common ones are HTTP on 80 and HTTPS on 443, among others). Banner grabbing is a useful technique within this process to read the service’s banner and guess the exact service type and version, but the overall goal—discovering which ports exist and what services they offer—is service discovery. DNS enumeration or zone transfers, on the other hand, deal with domain name data and don’t reveal the ports/services exposed by a web server.

Service discovery is about mapping a host’s open ports to the services running on them. It usually starts with scanning to see which ports are open, then identifying what service is listening on each port (for a web server, common ones are HTTP on 80 and HTTPS on 443, among others). Banner grabbing is a useful technique within this process to read the service’s banner and guess the exact service type and version, but the overall goal—discovering which ports exist and what services they offer—is service discovery. DNS enumeration or zone transfers, on the other hand, deal with domain name data and don’t reveal the ports/services exposed by a web server.