Table of Contents
Cisco Certified Network Associate CCNA
Introduction to Networking
What are the characteristics of a Network?
Answer:
1: Speed (How fast data is transmitted over the network).
2: Cost (General cost of components, installation, and maintenance).
3: Security (How secure the network is)?
4: Availability (Probability that the network will be available for use when required).
5: Scalability and Reliability (How well your network can accommodate more users and Mean Time Between Failures (MTBF))
Need for network security?
1: 60 to 80 percent of network misuse comes from inside.
2: Open and Close network (A Closed network does not allow a connection to public networks).
Classes of Attack:
1: Passive attack:
Traffic analysis, monitoring communication.
2: Active attack:
Attempts to break protection features like DoS.
3: Close-in:
Attempting to go close to physical proximity to networks, systems, or facilities.
4: Insider:
Malicious insiders steal or damage information.
Network Threats and Mitigation
Mitigating Common Threats
Physical Installations:
1: Room Lock (Lock is not the preventive control).
2: No access from the ceiling.
3: Electronic access control (Biometric).
4: CCTV.
5: Temperature and humidity control systems (HVAC).
6: UPS and backup generator.
Reconnaissance Attacks:
1: Discovery and mapping of systems to gather information.
2: Intruders look for vulnerable services.
3: Investigate the neighbourhood.
Access Attacks:
1: Exploit known vulnerabilities.
Password Attacks:
1: Repeated attempts like Brute-Force.
2: Disable on unsuccessful logins.
3: OTP like RSA SecureID hardware.
4: Strong password.
Open Systems Interconnection model (OSI)
1: Application Layer.
2: Presentation Layer.
3: Session Layer.
4: Transport Layer.
5: Network Layer.
6: Data link Layer.
7: Physical Layer.
Network Addressing
IP Address Classes:
There is total five classes in IP Address.
1: Class A: Network (8 Bits), Host (8 Bits), Host (8 Bits), Host (8 Bits).
2: Class B: Network (8 Bits), Network (8 Bits), Host (8 Bits), Host (8 Bits).
3: Class C: Network (8 Bits), Network (8 Bits), Network (8 Bits), Host (8 Bits).
4: Class D: Multicasting.
5: Class E: Research.
IPv4 Address Classes range:
Class A: 1 to 126
Class B: 128 to 191
Class C: 192: to 223
Class D: 224 to 239
Class E: 240 to 255
Ports
1: 0 to 1023 are well-known ports.
2: 1024 to 49151 are registered ports.
3: 49152-65535 are unregistered.
