Network+ N10-009

Layer 1 - Physical:

Receives the frames and data and sends them via the local media (copper wires, fiber-optic cables, etc.) to the switches, routers, etc., along the network path.

Layer 2 - Data link:

- Receives the packets and adds physical addressing by adding sender and receiver MAC addresses to each data packet.

- This information forms a unit called a frame.

Layer 3 - Network:

The routing layer (IP addresses, routers, packets).

Layer 4 - Transport:

The functions defined in this layer provide for the reliable transmission of data segments, as well as the disassembly and assembly of the data before and after transmission.

Layer 5 - Session:

- Establishes, manages, and terminates sessions between two communicating hosts.

- Synchronizes dialog between the presentation layers of the two hosts and manages their data exchange.

Layer 6 - Presentation:

- Ensures that info sent at application layer of one system is readable by the application layer of another system.

- May translate between multiple data formats by using a common format.

Layer 7 - Application:

- Closest to the user.

- Provides network services to the applications of the user, such as email, file transfer, and terminal emulation.

Router:

A device that forwards data packets between computer networks.

Switch:

A computer networking device that connects network segments.

Firewall:

A part of a computer system or network that is designed to block unauthorized access while permitting outward communication.

Intrusion detection system (IDS):

Monitors network traffic to identify possible malicious activity and log information about it.

Intrusion prevention system (IPS):

Sits behind the firewall and uses anomaly detection or signature-based detection to identify and respond to network threats.

Load Balancer:

Hardware or software that balances the load between two or more servers.

Proxy:

A system or router that provides a gateway between users and the internet.

Network-attached storage (NAS):

A server that is placed on a network with the sole purpose of providing storage to users, computers, and devices attached to the network.

Storage area network (SAN):

A high-speed network with the sole purpose of providing storage to other attached servers.

Wireless Access point (AP):

A device that enables wireless systems to communicate with each other, provided that they are on the same network.

Wireless Controller:

A central management console for all of the APs on a network.

Content delivery network (CDN):

- An information system that serves content to Web pages over the Internet.

- To reduce wait time, data is typically stored and served from many geographic locations.

Virtual private network (VPN):

A private data network that creates secure connections, or "tunnels," over regular Internet lines.

Quality of service (QoS):

Policies that control how much bandwidth a protocol, PC, user, VLAN, or IP address may use.

Time to live (TTL):

The maximum amount of time a packet is allowed to circulate through a network before it is destroyed.

Network functions virtualization (NFV):

Provisioning virtual network appliances, such as switches, routers, and firewalls, via VMs and containers.

Virtual private cloud (VPC):

A private network segment made available to a single cloud consumer within a public cloud.

Network security groups:

Allows you to filter network traffic. Can contain multiple inbound and outbound security rules that enable you to filter traffic to and from resources.

Network security lists:

Consists of a set of ingress and egress security rules that apply to all the VNICs in any subnet that the list is associated with.

Internet gateway:

A device or node that connects networks by translating protocols.

Network address translation (NAT) gateway:

You can use this so that instances in a private subnet can connect to services outside your VPC, but external services cannot initiate a connection with those instances.

Public cloud:

Provides cloud services to just about anyone.

Private cloud:

Serves only one customer or organization and can be located on the customer's premises or off the customer's premises.

Hybrid cloud:

A mixed computing environment where applications are run using a combination of computing, storage, and services in different environments.

Software as a service (SaaS):

A form of cloud computing where a firm subscribes to a third-party software and receives a service that is delivered online.

Infrastructure as a service (IaaS):

Delivers hardware networking capabilities, including the use of servers, networking, and storage, over the cloud using a pay-per-use revenue model.

Platform as a service (PaaS):

Supports the deployment of entire systems including hardware, networking, and applications using a pay-per-use revenue model.

Scalability:

Refers to how well a system can adapt to increased demands.

Elasticity:

Refers to the ability of a cloud to automatically expand or compress the infrastructural resources on a sudden up and down.

Multitenancy:

A single instance of a system serves multiple customers.

Internet Control Message Protocol (ICMP):

- An IP network protocol used to determine if a particular service or host is available.

Transmission Control Protocol (TCP):

A protocol for sending packets that does error-checking to ensure all packets are received and properly ordered.

User Datagram Protocol (UDP):

A protocol for sending packets quickly with minimal error-checking and no resending of dropped packets.

Generic Routing Encapsulation (GRE):

Method of encapsulation of IP packet in a GRE header which hides the original IP packet.

Internet Protocol Security (IPSec):

A set of protocols developed to support the secure exchange of packets between hosts or networks.

Authentication Header (AH):

An IPsec protocol that authenticates that packets received were sent from the source identified in the header of the packet.

Encapsulating Security Payload (ESP):

An IPsec protocol that provides authentication, integrity, and encryption services.

Internet Key Exchange (IKE):

Method used by IPSec to create a secure tunnel by encrypting the connection between authenticated peers.

Unicast:

A form of message delivery in which a message is delivered to a single destination.

Multicast:

A form of transmission in which a message is delivered to a group of hosts.

Anycast:

A network addressing and routing method in which incoming requests can be routed to a variety of different locations or "nodes."

Broadcast:

Used to transmit a message to any reachable destination in the network without the need to know any information about the receiving party.

Frequency bands used by 802.11 networks include:

- 5.0 GHz.

- 2.4 GHz.

IEEE 802.11a wireless standard:

- 5.0 GHz frequency band.

- Maximum data signaling rate of 54 Mbps.

IEEE 802.11b wireless standard:

- 2.4 GHz frequency range.

- Maximum data signaling rate of 11 Mbps.

IEEE 802.11g wireless standard:

- 2.4 GHz frequency range.

- Maximum data signaling rate of 54 Mbps.

IEEE 802.11n wireless standard:

- 2.4 GHz frequency band.

- 5.0 GHz frequency band.

- Maximum data signaling rate of up to 600 Mbps.

- Multiple Input / Multiple Output (MIMO).

IEEE 802.11ac (WiFi 5) wireless standard:

- 5.0 GHz frequency band.

- Maximum data signaling rate of up to 6.933 Gbps.

- Multi-User Multiple Input / Multiple Output (MU-MIMO).

IEEE 802.11ax (WiFi 6) wireless standard:

- 2.4 GHz frequency band.

- 5.0 GHz frequency band.

- Maximum data signaling rate of up to 9.607 Gbps.

- Multi-User Multiple Input / Multiple Output (MU-MIMO).

Refers to directional antenna types suitable for long-range point-to-point bridging links?

- Yagi antenna.

- Dish antenna.

- Parabolic antenna.

Cellular:

- Radio network distributed over land through cells where each cell includes a fixed location transceiver known as base station.

- These cells together provide radio coverage over larger geographical areas.

IEEE 802.3af:

PoE (Power over Ethernet).

IEEE 802.3at:

PoE+.

IEEE 802.3bt:

- PoE++.

- 4PPoE.

Single-mode Fiber (SMF):

- Uses lasers.

- Longer distance and smaller diameter.

- Used in telecom and CATV networks.

Multimode fiber (MMF):

- Uses LEDs.

- Shorter distance and wider diameter.

- Used in LAN, security systems, and CCTV.

Direct attach copper (DAC) cable:

Allows direct communication between devices over copper wire.

Twinaxial cable:

A variant of coaxial cables, which features two inner conductors instead of one and is used for very-short-range high-speed signals.

Coaxial cable:

Insulated copper wire; used to carry high-speed data traffic and television signals.

Plenum vs. Non-Plenum Cables:

- Plenum cables are engineered with fire-retardant materials, emitting minimal smoke and toxic fumes in case of fire.

- Non-plenum cables often come at a lower cost than plenum cables.

Ethernet:

A physical and data layer technology for LAN networking.

Protocol:

A set of rules governing the exchange or transmission of data between devices.

Fibre Channel (FC):

- A high-speed data transfer protocol providing in-order, lossless delivery of raw block data.

- Primarily used to connect computer data storage to servers in storage area networks (SAN) in commercial data centers.

Small form-factor pluggable (SFP):

Fiber optic transceiver module type supporting duplex 1 Gbps (SFP) or 10 Gbps (SFP+) links.

Quad small form-factor pluggable (QSFP):

- Small, high-density pluggable interface used for high-speed data transmission.

- It connects between network devices and fiber optic or copper cables, providing multiple channels for simultaneous data transmission.

Local Connector (LC):

Fiber-optic cable connector that corresponds to the mini form-factor standard.

Subscriber connector (SC):

Push/pull connector used with fiber optic cabling.

Straight tip (ST):

Bayonet-style twist-and-lock connector for fiber optic cabling.

Multi-fiber push on (MPO):

Accommodates multiple fibers in a single physical connector interface.

Registered jack (RJ) 11:

Connector wired for one telephone line.

RJ45:

A common connector or plug used on the end of the network cable.

F-type:

Used with Coaxial Cabling.

Mesh Topology:

Every computer connects to every other computer; no central connecting device is needed.

Hybrid Topology:

A physical topology that combines characteristics of more than one simple physical topology.

Star/hub and spoke:

A network topology where all devices are connected to a central hub or switch, which manages the data flow between them.

Spine and leaf:

A newer network topology that consists of just two layers.

Point to point:

A data transmission that involves one transmitter and one receiver.

Three-Tier Hierarchical Model:

- Access layer: Provides access points for hosts to connect to the network.

- Distribution layer: Acts as an intermediary between the Core Layer and the Access Layer, and keeps local traffic confined to local networks.

- Core layer: Handles and transports huge amounts of data quickly and reliably and connects multiple end networks together.

Collapsed core:

A network design where the core and distribution layers are collapsed or combined into a single layer of switches.

North-south traffic flow:

Data transmission pattern that describes data flow between local network endpoints and external networks and services, such as the World Wide Web, cloud services, etc.

East-west traffic flow:

Transfer of data packets from server to server within a data center.

Automatic Private IP Addressing (APIPA):

A networking feature in operating systems that enables DHCP clients to self-configure an IP address and subnet mask automatically when a DHCP server isn't available.

RFC1918:

Defined the 3 ranges of private IPv4 Addresses:

- 10.0.0.0 - 10.255.255.255 /8

- 172.16.0.0 - 172.31.255.255 /16

- 192.168.0.0 - 192.168.255.255 /32

Loopback/localhost:

- Used to test the IP stack on the local computer.

- Can be any address from 127.0.0.1 through 127.255.255.254.

Public vs. private network:

- Public networks are "open" access networks prioritizing accessibility and availability over network performance and security.

- Private networks are "closed" and secure networks prioritizing network safety, confidentiality, and performance over accessibility and ease of use.

Subnetting:

The act of dividing a network into smaller logical subnetworks.

Variable Length Subnet Mask (VLSM):

- The capability to specify a different subnet mask for the same Class A, B, or C network number on different subnets.

- VLSM can help optimize available address space.

Classless Inter-domain Routing (CIDR):

- Allows network administrators to expand the number of network nodes assigned to an IP address.

- Based on the idea that IP addresses can be allocated and routed based on their network prefix rather than their class.

Class A IPv4:

1.x.x.x to 126.x.x.x

Class B IPv4:

128.x.x.x - 191.x.x.x

Class C IPv4:

192.x.x.x - 223.x.x.x

Class D IPv4:

224.x.x.x - 239.x.x.x

Class E IPv4:

240.x.x.x - 255.x.x.x