Download CCNA Chapter 1 CCNA Chapter 1 and more Exams Computer Networks in PDF only on Docsity!
CCNA Chapter 1
What is a network? - A network is all of the components involved in connecting computers and applications across small and large distances to increase productivity and give easy access to information. What resources are commonly shared across a network? - Data and applications, printers, network storage components, and backup storage components. What 7 characteristics should be considered when creating or maintaining a network? - Cost, security, speed, topology, scalability, reliability, and availability. How is network Reliability measured? - As the Mean time between Failures - or MTBF - which is a measurement used to indicate the likelihood of a component failing. How is network Availability measured? - As an "uptime" annual percentage that is calculated by taking the number of minutes the network is available and dividing it by the number of minutes in a year, which is 525,600. In a network, what is a "network-aware" application? - An application that allows you to access and use resources that are not located on your local computer. What are 3 common networking applications? - E-mail, FTP, and web applications. What do Protocols do? - Protocols are used to implement applications. Name 5 common network protocols. - Simple Mail Transfer Protocol (SMTP), Internet Message Access Protocol version 4 (IMAP4), Post Office Protocol 3 (POP3), File Transfer Protocol (FTP), and Hypertext Transfer Protocol (HTTP) What specific requirements are needed for large data transfers for things such as Voice over IP (VOIP) and video Quality of Service (QoS)? - Minimal delay and latency. What 3 component categories do you need to build a network? - Computers, networking, and media. Name 9 common network components. - "Hubs, bridges, switches, routers, firewalls, wireless access points, modems, NT1s (Network Terminator Type 1 is an ISDN network termination device), and channel service units/data service units (CSU/DSUs)."
What are network security appliances? - Specialized network components that typically provide many security functions. Name and describe the 4 types of networking locations. -
- Small Office/Home Office (SOHO) - Home or small office with a handful of people. 2) Branch Office - Users are connected in a small area that is geographically separated from the corporate office. 3) Mobile Users - Can connect to the network from any location, LAN, or Wan. 4) Corporate or Central Office - Most of the network users and resources are located in one location. What are Local area networks (LANs) used for? - To connect networking devices that are in a very close geographic area. Name 9 network devices commonly found in a LAN. - PCs, file servers, hubs, bridges, switches, routers, multilayer switches, voice gateways, and firewalls. Name 6 types of media used in a LAN. - Copper and fiber cabling. Ethernet, Fast Ethernet (FE), Gigabit Ethernet (GE), Token Ring, and fiber distributed data interface (FDDI). What is the de facto standard for LAN-based networks? - Ethernet. What are Wide Area Networks (WAN's) used for? - To connect LAN's together, even when they are separated by a large distance. Where are WAN's leased from? - Carrier networks, such as telephone companies and Internet service providers. What are the 4 basic type of WAN connections or circuits? - Circuit-switched, cell-switched, packet-switched, and dedicated connections. Name 9 services available via a WAN. - Analog dialup, asynchronous transfer mode (ATM), dedicated circuits, cable, digital subscriber line (DSL), Frame Relay, Integrated Services Digital Network (ISDN), Switched Multi-megabit Data Services (SMDS), and X. Give 2 examples of circuit-switched services. - Analog dial-up and ISDN. Give 2 examples of cell-switched services. - ATM and SMDS. Give 2 examples of packet-switched services. - Frame Relay and X.25. Describe a circuit-switched service. -
Describe a star topology. - A central device has many point-to-point connections to other components. Star topologies are used in environments where many different devices need to be connected, with a hub or switch at the center of the star. What is the main disadvantage of a star topology, and how can it be overcome? - If the center of the star fails, no devices can communicate. Overcome by using an extended star topology that is multiple interconnected star topologies. Describe a bus topology. - All components are connected to and share a single wire using special types of connectors or transceivers. Describe a ring topology. - Device one connects to device two, device two connects to device three, and so on to the last device, which connects back to the first device. Ring topologies can be implemented with a single ring or a dual ring. When are dual ring topologies used, and what is the benefit? - When redundancy is needed, and the benefit is that in a dual-ring topology, the ring can loop back on itself. Give an example of a media technology that uses dual rings to connect computer components. - Fiber distributed data interface (FDDI). What does a physical topology describe? - How network components are physically cabled together. What does a logical topology describe? - How network components communicate across the physical topology. Describe the physical and logical topologies of Ethernet media. - Physical: bus, star, or point to point Logical: bus Describe the physical and logical topologies of FDDI media. - Physical: ring Logical: :ring Describe the physical and logical topologies of Token Ring media. - Physical: star Logical: ring Describe the mesh topology in a network environment. - It describes how network components are connected together, and can be either full or partial. Describe partial meshing. - Every network component is NOT connected to every other component. Describe full meshing. - Every network component is connected to every other network component.
What type of mesh topology does a WAN use, and why? - WAN's typically use a partial mesh topology in order to reduce the cost of connecting components and locations. What is the formula that is used to determine the number of links needed to fully mesh a WAN? - N x (N-1) divided by 2, where N is the number of locations. What does a security policy define, and what is derived from it? - What people can and can't do with network components, and a security solution is derived from the security policy. Name the 5 classes of network attack. - Passive, active, insider, distributed, and close-in. What is a network Adversary, and give 7 examples. - An adversary is a person or persons interested in attacking your network. Common adversaries include disgruntled employees, unskilled and skilled hackers, criminals, other countries, terrorists, and competing companies. Describe a passive network attack. - An adversary monitors monitors unencrypted traffic and looks for clear-text passwords and sensitive information that can be used in other types of attacks. Describe an active network attack. - An adversary tries to bypass or break into secured systems using stealth, viruses, worms, or Trojan horses, or by exploiting a discovered security vulnerability. Describe a distributed network attack. - An adversary introduces code, such as a Trojan horse or back-door program, to a "trusted" component or software that will later be distributed to many other companies and users. Describe an insider network attack. - An inside adversary attempts to eavesdrop, copy, or cause damage to information, often using a sniffing tool such as Wireshark. Describe a close-in network attack. - An adversary attempts to get physically close to network components, data, and systems in order to learn more about a network or to cause damage. What are 4 categories of common network threats? - Physical installations, reconnaissance attacks, access attacks, and denial of service (DoS) attacks What are 4 types of physical installation threats? - Hardware, electrical, environmental, and maintenance. What are hardware threats? -
Maintain parts on hand, clearly label and run cables, perform electrostatic discharge procedures, and have idle timeouts on any network component that has a login. What are the 2 types of security controls? - Physical or logical. Describe 4 physical security controls. - Sign in and out logs, locks, guards, and doors. Describe 3 logical security controls. - Idle timeout on logins, passwords, and authentication methods. What is a reconnaissance attack? - When an adversary tries to learn information about a network. What are 3 tools that adversaries use in reconnaissance attacks? - Social engineering, scanning tools, and packet sniffers. How do you mitigate a social engineering attack? - Network users should go through proper training about the kinds of information that they can or can't share with other people. What are 2 ways to mitigate scanning and packet sniffing attacks? - Access control mechanisms such as firewalls, and IDS/IPS. What is an access attack? - When someone tries to gain unauthorized access to a component, to unauthorized information on a component, or to increase their privileges on a network component. What is the most common type of access attack? - A password attack when an adversary tries to guess a valid password for an existing account. What are 2 types of password attacks? - Using a password cracking program that will use a dictionary to guess common passwords or use a brute-force approach by guessing every combination of numbers, letters, and special characters. What is the purpose of network filters, such as Access Control Lists? - To restrict access to network components and their information, such as only allowing accounting employees access to the accounting server. How to you mitigate Trojan Horse attacks? - Using an IDP/IPS and anti-spyware software. Name 2 good network password practices. - Passwords should be at least 10 characters long, and users shouldn't be allowed to use the same password on different network components. What does a token card do? -
It uses a one-time password (OTP) that generates a different, dynamic password each time a user logs into a system. What is a good encryption solution to guard network login information? - "Encrypt information between two network components so that login credentials cannot be viewed; for example, it is better to use SSH instead of telnet for remote access because SSH encrypts the session traffic." What is a Denial of Service (DoS) attack? - When an adversary reduces the level of operation or service, preventing access to, or completely crashing a network component or service. Describe a possible DoS attack scenario. - Flooding millions of packets or injecting code into an application or overrunning the buffer(s) of an application, causing it to crash. How can DoS attacks be mitigated? - Using access control mechanisms such as packet filtering to control access to a system. What are 2 types of DoS attacks? - Flood attacks, such as Internet Control Message Protocol (ICMP) and TCP SYN flooding, as well as buffer overrun attacks How does rate limiting protect a network? - It ensures that a system doesn't become overwhelmed by a flood attack. Describe 3 types of network attacks and their solutions, including recommended devices. -
- Reconnaissance - Mitigation: ACL's Devices: IPS, IDS, routers 2) Access - Mitigation: Authentication, port security, virtual LANs (VLANs), ACLs, virtual private networks (VPNs) Devices: Switches, routers, firewalls, IPS, IDS 3) DoS - Mitigation: ACL's Devices: IPS, IDS, firewalls, routers. Which network characteristic is concerned about MTBF? - Reliability. What describew users working from home? - SOHO A __________ topology uses a single cable to connect all devices together. - Bus __________ has both physical and logical ring topologies. - FDDI Ethernet __________ has/have both a physical and logical bus topology. - 10Base2 and 10Base A __________ topology describes how devices communicate with each other. - Logical
