Quick Answer
The answer is RPKI, BGP prefix filtering, and MD5 authentication between BGP peers. RPKI prevents route hijacking by using cryptographically signed Route Origin Authorizations (ROAs) to validate that an autonomous system is authorized to originate specific IP prefixes, allowing routers to reject any BGP announcement that does not match the registered origin AS. On the CISSP exam, this topic tests your understanding of network security controls within the Communication and Network Security domain, often appearing in questions that distinguish between authentication mechanisms and origin validation. A common trap is confusing MD5 authentication—which only secures the peer session—with RPKI’s origin validation; remember that MD5 protects the BGP session itself, while RPKI protects the route’s legitimacy. For a memory tip, think “RPKI roots out rogue origins” to recall that it verifies the source of a prefix announcement.
This CISSP practice question tests your understanding of communication and network security. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Which three BGP security mechanisms help protect against route hijacking? (Choose THREE.)
Resource Public Key Infrastructure (RPKI)
Validates the origin AS of IP prefixes.
BGP Flowspec
Why wrong: Used for traffic filtering and DDoS mitigation.
Prefix filtering on edge routers
Blocks unauthorized route announcements.
BGP MED attribute
Why wrong: Influences inbound path selection, not security.
MD5 authentication between BGP peers
Ensures secure BGP session between neighbors.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Resource Public Key Infrastructure (RPKI)
RPKI is correct because it uses cryptographically signed Route Origin Authorizations (ROAs) to validate that an AS is authorized to originate specific IP prefixes. This prevents route hijacking by allowing routers to reject BGP announcements that do not match the registered origin AS.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Resource Public Key Infrastructure (RPKI)
Why this is correct
Validates the origin AS of IP prefixes.
Related concept
Read the scenario before looking for a memorised answer.
BGP Flowspec
Why it's wrong here
Used for traffic filtering and DDoS mitigation.
Prefix filtering on edge routers
Why this is correct
Blocks unauthorized route announcements.
Related concept
Read the scenario before looking for a memorised answer.
BGP MED attribute
Why it's wrong here
Influences inbound path selection, not security.
MD5 authentication between BGP peers
Why this is correct
Ensures secure BGP session between neighbors.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
ISC2 often tests the distinction between BGP security mechanisms that prevent hijacking (RPKI, prefix filtering, MD5 authentication) versus those that influence routing policy or traffic engineering (MED, Flowspec), leading candidates to mistakenly select MED or Flowspec as hijacking protections.
Detailed technical explanation
RPKI relies on a hierarchical public key infrastructure where Regional Internet Registries (RIRs) issue ROAs that bind a prefix to an AS number. Routers perform ROV (Route Origin Validation) by checking the ROA; if the announcement is 'Invalid' (prefix-AS mismatch), it can be rejected. A subtle behavior: RPKI does not protect against AS path forgery (e.g., prepending fake hops), only against origin hijacking.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A developer is choosing between AES-256 (symmetric) and RSA-2048 (asymmetric) for encrypting a large file that will be sent to a partner. Symmetric encryption is fast but requires key exchange; asymmetric is slower but solves the key distribution problem. A hybrid approach — encrypt the file with AES, encrypt the AES key with RSA — is standard. Questions like this test whether you understand when each approach applies.
What to study next
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FAQ
Communication and Network Security — This question tests Communication and Network Security — Read the scenario before looking for a memorised answer..
The correct answer is: Resource Public Key Infrastructure (RPKI) — RPKI is correct because it uses cryptographically signed Route Origin Authorizations (ROAs) to validate that an AS is authorized to originate specific IP prefixes. This prevents route hijacking by allowing routers to reject BGP announcements that do not match the registered origin AS.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 30, 2026
This CISSP practice question is part of Courseiva's free ISC2 certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the CISSP exam.
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