ITPEC FE Subject A October 2025 Question 29
ITPEC FE Subject A October 2025 — Question 29 of 60
DNS Cache Poisoning — attacker injects a fake IP into a DNS cache server, redirecting users to a malicious server.
The attacker recorded server X's IP on Company B's DNS cache as the address for Company A's web server FQDN.
- •Company B's employees use Company B's DNS → it's poisoned
- •They try to reach Company A's web server → DNS returns server X's IP
- •They unknowingly connect to server X
Why not others:
- (a) Company A employees use Company A's DNS — not poisoned
- (b) Same reason — Company A's DNS is clean
- (d) The poisoned record is for Company A's FQDN, not Company B's — accessing Company B's own server returns the correct IP
Key rule: DNS cache poisoning affects users of the poisoned DNS server, only when they query the specific domain whose record was tampered with.
AI-generated — may contain errors
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