Examkin

Question

Difficulty: HardCommon Ports and Protocols

Match each network service requirement on the left with its corresponding default port number and transport layer protocol on the right.

  • Directory service queries requiring implicit encryption via TLSTCP port 636
  • Network clock synchronization across distributed network infrastructureUDP port 123
  • Encrypted remote command-line administration and secure file transferTCP port 22
  • Initial key exchange and Security Association negotiation for IPsec VPNsUDP port 500

Answer

Directory queries via TLS matches TCP port 636; Network clock synchronization matches UDP port 123; Encrypted remote administration matches TCP port 22; Initial key exchange for IPsec VPNs matches UDP port 500.
Each service requirement maps strictly to its standard port and transport protocol: encrypted LDAP queries require TCP port 636, time synchronization requires UDP port 123, secure remote management requires TCP port 22, and IPsec key exchange requires UDP port 500.

Step-by-Step Solution

1
Analyze secure directory service protocol requirements.
Identified LDAPS operating over TCP port 636.
Standard unencrypted LDAP uses TCP 389, while implicitly encrypted LDAPS mandates TCP port 636.
2
Analyze time synchronization protocol requirements.
Identified NTP operating over UDP port 123.
Clock synchronization requires low overhead without connection setup delays, necessitating UDP port 123.
3
Analyze secure CLI and file administration protocol requirements.
Identified SSH/SFTP operating over TCP port 22.
Secure Shell provides reliable encrypted interactive shell access and SFTP transport via TCP port 22.
4
Analyze IPsec VPN key negotiation protocol requirements.
Identified IKE operating over UDP port 500.
Internet Key Exchange Phase 1 Security Association setup uses ISAKMP over UDP port 500.

Key Concept

Standard Network Port Assignments and Transport Layer Selection
Rate this question

Topics

Common Ports and Protocols

More questions from this topic