A NULL scan sends a TCP packet with no flags set. It is used to identify open or filtered ports based on how the target responds.

An advanced persistent threat (APT) may be a broad term wont to describe AN attack campaign within which an intruder, or team of intruders, establishes a bootleg, long presence on a network so as to mine sensitive knowledge.
The targets of those assaults, that square measure terribly fastidiously chosen and researched, usually embrace massive enterprises or governmental networks. the implications of such intrusions square measure huge, and include:
Intellectual property thieving (e.g., trade secrets or patents)
Compromised sensitive info (e.g., worker and user personal data)
The sabotaging of essential structure infrastructures (e.g., information deletion) Total website takeovers Executing an APT assault needs additional resources than a regular internet application attack. The perpetrators square measure typically groups of intimate cybercriminals having substantial resource. Some APT attacks square measure government-funded and used as cyber warfare weapons.
APT attacks dissent from ancient internet application threats, in that:
They're considerably additional advanced.
They're not hit and run attacks-once a network is infiltrated, the culprit remains so as to realize the maximum amount info as potential.
They're manually dead (not automated) against a selected mark and indiscriminately launched against an outsized pool of targets.
They typically aim to infiltrate a complete network, as opposition one specific half.
More common attacks, like remote file inclusion (RFI), SQL injection and cross-site scripting (XSS), square measure oftentimes employed by perpetrators to ascertain a footing in a very targeted network. Next, Trojans and backdoor shells square measure typically wont to expand that foothold and make a persistent presence inside the targeted perimeter.

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.

WPA with TKIP suffers from vulnerabilities inherited from WEP, particularly the use of weak Initialization Vectors (IVs). CEH v13 explains that these weaknesses allow attackers to perform packet injection and partial decryption attacks.
Although WPA improved upon WEP, TKIP was designed as a temporary solution and still relies on predictable IV behavior. This makes Option C correct.
Lack of AES (Option A) explains why WPA is weaker than WPA2 but does not directly describe the exploit mechanism. Weak passwords (Option D) affect authentication, not packet injection. GTK predictability (Option B) is relevant but not the primary cause here.
CEH v13 explicitly states that IV reuse and predictability in TKIP enable practical attacks. Therefore, Option C is correct.