A network engineer is creating an Access Control List (ACL) on a core switch to restrict traffic from a network management workstation. The workstation must be allowed to dynamically query domain name resolutions from an internal server and establish encrypted command-line management sessions to remote routers. However, the policy must strictly prohibit the workstation from acting as a dynamic IP addressing service or establishing unencrypted legacy terminal sessions. Which of the following transport protocol and port combinations must be permitted outbound from the workstation to fulfill this security policy?
- UDP port 53 and TCP port 22Cevap
- BUDP port 67 and TCP port 23
- CUDP port 68 and TCP port 22
- DTCP port 53 and UDP port 23
Cevap
The firewall policy must explicitly permit outbound traffic targeted to UDP port 53 for DNS hostname resolution and TCP port 22 for encrypted SSH terminal management.
Standard DNS client queries use UDP port 53 to resolve domain names to IP addresses quickly without connection setup overhead. Secure Shell (SSH) uses TCP port 22 to establish an encrypted, reliable remote terminal connection. Therefore, permitting UDP port 53 and TCP port 22 satisfies both requirements.
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Anahtar Kavram
Port and protocol identification for secure administrative access (SSH/TCP 22) and core network infrastructure services (DNS/UDP 53 vs DHCP/UDP 67/68).
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