ECCouncil Updated 312-50v13 Exam Questions and Answers by alisha

DNS poisoning (also known as DNS cache poisoning) occurs when a malicious actor injects false DNS data into a DNS resolver's cache. The poisoned entry will persist for the duration of its TTL (Time To Live), which is defined in the DNS SOA (Start of Authority) record.

The SOA record contains several fields including:

Serial number

Refresh

Retry

Expire

Minimum TTL

The Minimum TTL value in the SOA record determines how long a DNS resolver should cache the DNS data — including any potentially poisoned data.

From CEH v13 Official Courseware:

Module 3: Scanning Networks

Topic: DNS Enumeration & Poisoning

CEH v13 Study Guide states:

“The SOA record includes a minimum TTL value that dictates how long DNS information should be cached by other DNS servers. If DNS cache poisoning occurs, the false information will persist until the TTL expires.”

Incorrect Options:

A: MX (Mail Exchange) defines mail servers, not TTLs.

C: NS (Name Server) specifies authoritative servers, not caching durations.

D: TIMEOUT is not a valid DNS resource record.

In CEH v13 Module 14: Cryptography, key escrow is discussed as a recovery mechanism where a third party securely holds a cryptographic key for retrieval if it’s lost.

Key Escrow Characteristics:

Common in enterprise environments for systems like BitLocker.

Keys are automatically backed up to Active Directory (AD) for future retrieval.

Ensures that encrypted data is not permanently lost due to forgotten or deleted keys.

Option Clarification:

A. Key archival: Storing old keys for audit/record-keeping.

B. Key escrow: Correct – Third-party or central storage for recovery purposes.

C. Certificate rollover: Replacement of expiring certificates.

D. Key renewal: Generating a new key after expiration or compromise.

ESP (Encapsulating Security Payload) in transport mode is used for end-to-end communication between hosts within the same LAN. It encrypts only the payload, not the header, ensuring confidentiality and integrity while maintaining efficient routing.

Reference – CEH v13 Official Study Guide:

Module 20: Cryptography

Quote:

“In ESP transport mode, only the data payload is encrypted, making it ideal for secure communication within a LAN where the IP header must remain intact for routing.”

Incorrect Options Explained:

B & C. Not valid IPSec modes.

D. AH tunnel mode ensures integrity but does not provide encryption.

===========

A cryptographic hash function is used to ensure data integrity. It generates a fixed-length output (digest) from any size of input data. If the data is modified in any way, the resulting hash will change. This allows systems to detect data tampering, ensuring that the data remains unaltered from its original form.

Reference – CEH v13 Official Study Guide:

Module 20: Cryptography

Quote:

“Hash functions are used to ensure the integrity of a message or file by producing a unique digest that changes if the data is modified.”

Incorrect Options:

A. Authentication ensures identity, not data integrity.

B. Confidentiality is achieved via encryption, not hashing.

C. Availability pertains to system uptime and accessibility, not hashes.

===========