Credential stuffing is the best match because the scenario highlights automated login attempts across many accounts with an unusually high success rate, occurring in the aftermath of a breach. In CEH-aligned system hacking concepts, credential stuffing is the automated testing of known username and password pairs- typically harvested from prior breaches-against a different service. Because many users reuse passwords across sites, attackers often achieve a higher-than-normal success rate compared to guessing-based attacks.
This "high success rate" across numerous accounts is a key indicator that the attacker is not randomly guessing, but replaying valid credentials at scale using bots or automation frameworks.
Password spraying differs in that the attacker tries a small set of common passwords (or one password) across many accounts to avoid lockouts. Spraying generally yields a lower success rate and is driven by guessing rather than replaying known credential pairs. A brute force attack is even noisier and typically involves repeated guessing for a single account or small set of accounts; it is both slower and far less likely to produce a high success rate across many users in a short period. Phishing attacks can lead to account takeovers, but the pattern described would more often show targeted victims and varied sources rather than broad, automated, multi-account authentication bursts with consistently successful logins.
CEH defensive guidance emphasizes layered controls: enforce MFA, monitor for abnormal login velocity and credential reuse indicators, deploy bot detection and rate limiting, use breached-password checks, implement adaptive authentication, and tune lockout and detection policies to disrupt automated credential replay without enabling denial-of-service against legitimate users.

CEH's Malware Analysis module outlines a structured approach:
* Identify suspicious indicators (e.g., JavaScript, OpenAction)
* Extract and analyze embedded objects
* Determine behavior and exploit logic
PDFStreamDumper allows analysts to extract JavaScript code and embedded objects for detailed inspection.
Option B is correct.
Option A is useful but insufficient for deep analysis.
Option C only aids identification, not behavior understanding.

The correct answer is DNS interrogation. CEH reconnaissance guidance explains that active footprinting involves direct interaction with the target environment, which can generate logs or alerts. DNS interrogation is an active technique used to query name servers for information about domain structure, hostnames, mail servers, subdomains, and other records that reveal how public-facing systems are logically arranged. The question specifically says Justin is retrieving structural details about the organization's public-facing systems and that his activity is logged by the target, which is consistent with active DNS queries. Network or port scanning is also active, but it focuses on discovering open ports and reachable services rather than the logical naming and organizational structure of public systems. Social engineering is human-focused, and user and service enumeration typically aims at accounts or system services rather than domain structure. CEH materials repeatedly emphasize DNS as a rich reconnaissance source because records such as A, MX, NS, TXT, and SOA can reveal infrastructure relationships and naming conventions. Since the goal is to understand how the organization's internet-facing systems are organized and represented, DNS interrogation is the best fit.

Padding oracle attacks exploit systems that reveal differences in error responses when incorrectly padded ciphertext is submitted. CEH explains that these variations allow attackers to iteratively determine valid padding bytes and ultimately decrypt or modify encrypted data without knowledge of the key.

The correct answer is DNS Cache Poisoning. CEH network security material explains that cache poisoning occurs when a DNS server is tricked into storing fraudulent name-to-IP mappings in its cache. Once the poisoned entry is cached, many users querying that DNS service receive the same false resolution until the cache is flushed, expires, or the service is restarted. That maps directly to the scenario: multiple internal clients receive the same incorrect IP address for a legitimate domain, and the issue disappears after the organization's name resolution service is restarted. Intranet DNS spoofing typically involves local interception and very fast forged replies on a LAN, while proxy server DNS poisoning changes browser-side proxy behavior, and internet DNS spoofing usually involves altering a host's DNS configuration or redirecting it to a malicious resolver. The persistence across many users and the recovery after DNS service restart are the most important clues, because they indicate poisoned cached records on the resolver itself rather than isolated endpoint tampering. CEH guidance highlights that DNS cache poisoning can silently redirect users to counterfeit systems while appearing to resolve legitimate domain names normally.