The SecOps Group Certified Network Security Practitioner CNSP Exam Questions

Answer : C

SNMP community strings authenticate access, with defaults posing security risks if unchanged.

Why C is correct:

A: 'public' is the standard read-only default, per SNMP specs and CNSP.

B: 'private' is the standard read-write default, also per SNMP and CNSP.

Both are true, making C the answer.

Why other options are incorrect:

1, 2: Exclude one true statement each.

4: Both statements are true, so 'none' is wrong.

Answer : D

Network segmentation isolates network zones for security, but certain techniques can circumvent these controls, a focus of CNSP penetration testing.

Why D is correct:

A: DNS tunneling encodes data in DNS queries, bypassing segmentation via legitimate DNS traffic.

B: VLAN hopping exploits switch misconfigurations (e.g., double tagging) to access other VLANs.

C: Covert channels use hidden communication paths (e.g., timing channels) to evade segmentation.

All are valid techniques per CNSP for testing segmentation controls.

Why other options are incomplete: A, B, or C alone exclude other viable methods, making D the comprehensive answer.

Answer : A

UDP is a connectionless protocol, and its behavior when a packet reaches a port depends on whether the port is open or closed. Without a firewall altering the response, the standard protocol applies.

Why A is correct: When a UDP packet is sent to a closed port, the host typically responds with an ICMP Type 3 (Destination Unreachable), Code 3 (Port Unreachable) message, indicating no service is listening. CNSP notes this as a key indicator in port scanning.

Why other options are incorrect:

B: RST packets are TCP-specific, not used in UDP.

C: No response occurs for open UDP ports unless an application replies, not closed ports.

D: A is correct, so 'none of the above' is invalid.

Answer : A

Port 111/TCP is the default port for the RPC (Remote Procedure Call) portmapper service on Unix systems, which registers and manages RPC services.

Why A is correct: Running rpcinfo -p <hostname> queries the portmapper to list all registered RPC services, their programs, versions, and associated ports. This is a logical next step during a security audit or penetration test to identify potential vulnerabilities (e.g., NFS or NIS services). CNSP recommends this command for RPC enumeration.

Why other options are incorrect:

B . Telnet to the port to look for a banner: Telnet might connect, but RPC services don't typically provide a human-readable banner, making this less effective than rpcinfo.

C . Telnet to the port, send 'GET / HTTP/1.0' and gather information from the response: Port 111 is not an HTTP service, so an HTTP request is irrelevant and will likely fail.

D . None of the above: Incorrect, as A is a valid and recommended step.

Answer : A

In Unix-based systems (e.g., Linux), the ifconfig command is historically used to configure network interfaces, including changing the Media Access Control (MAC) address of an Ethernet adapter. The correct syntax to set a new MAC address for an interface like eth0 is ifconfig eth0 hw ether AA:BB:CC:DD:EE:FF, where hw specifies the hardware address type (ether for Ethernet), followed by the new MAC address in colon-separated hexadecimal format.

Why A is correct: The hw ether argument is the standard and correct syntax recognized by ifconfig to modify the MAC address. This command temporarily changes the MAC address until the system reboots or the interface is reset, assuming the user has sufficient privileges (e.g., root). CNSP documentation on network configuration and spoofing techniques validates this syntax for testing network security controls.

Why other options are incorrect:

B: hdw is not a valid argument; it's a typographical error and unrecognized by ifconfig.

C: hdwr is similarly invalid; no such shorthand exists in the command structure.

D: hwr is incorrect; the full keyword hw followed by ether is required for proper parsing.

Answer : D

TCP (Transmission Control Protocol) uses a three-way handshake (SYN, SYN-ACK, ACK) to establish connections, as per RFC 793. When a client sends a SYN packet to a port:

Open Port: The server responds with SYN-ACK.

Closed Port (no firewall): The server sends an RST (Reset) packet, often with ACK, to terminate the attempt immediately.

However, when a firewall is present, its configuration dictates the response. Modern firewalls typically operate in stealth mode, using a 'drop' rule for closed ports rather than a 'reject' rule:

Drop: Silently discards the packet without replying, resulting in no response. The client experiences a timeout (e.g., 30 seconds), as no feedback is provided.

Reject: Sends an RST or ICMP 'Port Unreachable,' but this is less common for security reasons, as it confirms the firewall's presence.

For a closed TCP port behind a firewall, 'no response' (drop) is the standard behavior in secure configurations, minimizing information leakage to attackers. This aligns with CNSP's focus on firewall best practices to obscure network topology during port scanning (e.g., with Nmap).

Why other options are incorrect:

A . A FIN and an ACK packet: FIN-ACK is used to close an established TCP connection gracefully (e.g., after data transfer), not to respond to an initial SYN on a closed port.

B . RST and an ACK packet: RST-ACK is the host's response to a closed port without a firewall. A firewall's drop rule overrides this by silently discarding the packet.

C . A SYN and an ACK packet: SYN-ACK indicates an open port accepting a connection, the opposite of a closed port scenario.

Real-World Context: Tools like Nmap interpret 'no response' as 'filtered' (firewall likely present) vs. 'closed' (RST received), aiding in firewall detection.

Answer : C

SSL/TLS protocols secure network communication, but older versions have vulnerabilities:

SSLv2 (1995): Weak ciphers, no handshake integrity (e.g., MITM via DROWN attack, CVE-2016-0800). Deprecated by RFC 6176 (2011).

SSLv3 (1996): Vulnerable to POODLE (CVE-2014-3566), weak block ciphers (e.g., RC4). Deprecated by RFC 7568 (2015).

TLSv1.0 (1999, RFC 2246): Inherits SSLv3 flaws (e.g., BEAST, CVE-2011-3389), weak CBC ciphers. Deprecated by PCI DSS (2018) and RFC 8996 (2021).

TLSv1.1 (2006, RFC 4346): Improved over 1.0 but lacks modern cipher suites (e.g., AEAD). Deprecated with 1.0 by RFC 8996.

TLSv1.2 (2008, RFC 5246): Secure with strong ciphers (e.g., AES-GCM), widely used today.

TLSv1.3 (2018, RFC 8446): Latest, removes legacy weaknesses, mandatory forward secrecy.

Why other options are incorrect:

A: Correct but incomplete without B.

B: Correct but incomplete without A.

D: Incorrectly includes TLSv1.2 and 1.3, which are secure and recommended.

Real-World Context: POODLE forced mass SSLv3 disablement in 2014; TLS 1.0/1.1 deprecation hit legacy systems in 2021.