CCNA Plan

CCNA practice question: Security Fundamentals

Security FundamentalsDifficulty 3/5

Which statement correctly contrasts RADIUS and TACACS+?

  1. ARADIUS uses TCP 49 and encrypts the entire packet body
  2. BTACACS+ uses TCP 49, encrypts the entire packet body and separates authorization from authentication
  3. CTACACS+ uses UDP 1812 and encrypts only the password
  4. DBoth use UDP and are functionally identical
Show answer and rationale

Correct: B. TACACS+ (Cisco) runs over TCP 49, encrypts the whole payload, and separates AAA functions, enabling per-command authorization. RADIUS uses UDP 1812/1813, encrypts only the password, and combines authentication and authorization.

  • A — Those are TACACS+ properties.
  • C — UDP 1812 and password-only encryption describe RADIUS.
  • D — They differ in transport, encryption and function separation.

Concept being tested

Threats and mitigation, device access control, password policy, IPsec/VPN concepts, ACLs, Layer 2 security (DHCP snooping, DAI, port security), AAA, wireless security and WPA2/WPA3. — 15% of the exam. Study guide for Security Fundamentals.

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Primary references

  1. CCNA Exam v1.1 (200-301) Exam Topics — Cisco Systems · primary · retrieved 2026-09-21, verified 2026-09-21
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