Cybersecurity Attacks and Network Security

VLANs are configured on switches to segment broadcast domains. While routers can interconnect VLANs via router-on-a-stick or Layer 3 switching, the actual VLAN configuration (assigning ports to VLANs, creating VLAN IDs) happens on the switch itself. Hubs are Layer 1 devices and cannot create VLANs.

Historically, Cisco devices shipped with default credentials of username 'cisco' and password 'cisco' (or blank username with 'cisco' as password). This is well-documented though modern security best practices require immediate change of these defaults.

VPNs use both symmetric and asymmetric encryption. Asymmetric encryption (RSA, Diffie-Hellman) is used during the key exchange/handshake phase to securely negotiate symmetric keys. Symmetric encryption (AES, 3DES) is then used for bulk data transfer because it's much faster. Hashing provides integrity, not encryption.

IPv6 was designed with IPsec as an integral, mandatory part of the protocol suite, whereas IPv4 treats IPsec as an optional add-on. This native integration in IPv6 makes security implementation more standardized and ubiquitous.

In security terminology, DOS stands for Denial-of-Service attack, which floods a target with traffic to make resources unavailable. While DOS historically meant Disk Operating System, the question specifies the security context. Option C is a government department, and option D is a fabricated expansion not used in security.

Vishing (voice phishing) is a social engineering attack that uses telephone services to deceive victims. Unlike email-based phishing, vishing manipulates victims through voice calls, often spoofing caller ID to appear legitimate. Option B is the broader category, while option D is the technology used, not the attack itself.

Penetration testing involves actively exploiting vulnerabilities to identify security weaknesses in hardware, software, or configurations. Unlike vulnerability assessment (option B), which identifies potential issues, pentesting demonstrates their impact through exploitation. Options A and C are generic terms that don't specifically involve exploiting vulnerabilities.

DNS poisoning (also called DNS spoofing) is an attack where the victim is redirected to a falsified DNS location. The attacker corrupts the DNS cache or response to redirect users to malicious sites. 'DNS falsifying' is not standard terminology, 'DNS caching' is a normal function, and 'DNS cracking' is not a recognized attack type.