Troubleshooting Network Infrastructure

Question 1

Switching Errors

Answer 1

Occur when data packets are misdirected or dropped as they move through a network switch

Question 2

Broadcast Storms

Answer 2

Happen when there is a layer 2 network loop, which often occurs due to improper configuration of the STP

Question 3

VLAN Mismatch

Answer 3

Occurs when two switches connected by a trunk are configured with different VLAN settings

Question 4

Duplex Mismatch

Answer 4

Occurs when the two ends of a network link have different duplex settings

Question 5

Routing Errors

Answer 5

Typically caused by misconfigurations, incorrect routing tables, or unstable network conditions

Question 6

Routing Loops

Answer 6

Happen when a packet gets stuck in a continuous cycle between routers without ever reaching its destination. Can be caused by incorrect routing table entry

Question 7

Incorrect Subnet Masks

Answer 7

Occur when the subnet mask associated with an IP address is not configured correctly

Question 8

Route Flapping

Answer 8

Occurs when a network route frequently changes state, causing instability in routing tables

Question 9

VPN and Tunnel Errors

Answer 9

Occur when encrypted communication tunnels face disruptions due to misconfigurations, expired credentials, or encryption failures

Question 10

Insecure Routing

Answer 10

Occurs when routing protocols or configurations lack proper security measures

Question 11

Configuration Drift

Answer 11

Gradual and often unnoticed changes in network configurations over time

Question 12

Signature-Based Detection

Answer 12

Compares network activity to known threat patterns, but it can miss new or sophisticated attacks

Question 13

Behavioral Analysis

Answer 13

Looks for deviations from normal network behavior, which can highlight suspicious activity even if no known threat signature is present

Question 14

Anomaly Detection

Answer 14

Uses machine learning to flag irregular patterns outside predefined baselines, adding protection

Question 15

DNSSEC

Answer 15

Domain Name System Security Extensions
Secure name resolution by digitally signing DNS data

Question 16

Zone Transfers

Answer 16

Replicate DNS databases but can be attacked if misconfigured

Question 17

DNS/Cache Poisoning

Answer 17

Attack where false DNS data is injected into a DNS resolver’s cache

Question 18

Sinkholing

Answer 18

Defensive technique that redirects malicious traffic to a controlled sinkhole server

Question 19

DNS Zone

Answer 19

Portion of the DNS namespace that a specific DNS server or a group of servers manages

Question 20

SPF

Answer 20

Sender Policy Framework
Specifies permitted mail servers for a domain to prevent email spoofing
Stored in DNS, specify domains and IP ranges authorized to send emails

Question 21

DKIM

Answer 21

Domain Keys Identified Mail
Adds a digital signature to verify email integrity and sender authenticity
Does not fully prevent spoofing, often combined with DMARC

Question 22

DMARC

Answer 22

Domain-based Message Authentication, Reporting, and Conformance
Provides email authentication and policy enforcement using SPF and DKIM results (ie if they fail SPF/DKIM, reject, quarantine, or mark as suspicious)

Question 23

S/MIME

Answer 23

Secure/Multipurpose Internet Mail Extensions
Enables encryption and digital signatures in email messages

Question 24

Network Access Control List Issues

Answer 24

Arise when incorrectly configured rules allow inappropriate network traffic or block legitimate network traffic

Question 25

Cipher Mismatch

Answer 25

Occurs when the client and server cannot agree on a cipher suite during the TLS handshake, leading to a failed or insecure connection

Question 26

What are some common PKI issues?

Answer 26

Misconfigured CAs Expired or improperly issued certificates Challenges in certificate revocation Improper key management or distribution