Network+ Flashcards
Transport Control Protocol/Internet Protocol - TCP/IP
- IP is the part that obtains the address to which data is sent.
- TCP is responsible for data delivery once that IP address has been found.
It also breaks down each message into packets, and those packets are then reassembled on the other end. In fact, each packet could take a different route to the other computer, if the first route is unavailable or congested.
In addition, TCP/IP divides the different communications tasks into layers. Each layer has a different function. Data goes through four individual layers before it is received on the other end (as explained in the following section). TCP/IP then goes through these layers in reverse order to reassemble the data and to present it to the recipient.
Why use protcols to communicate?
The purpose of the layers is to keep things standardized, without numerous hardware and software vendors having to manage communication on their own. It’s like driving a car: All the manufacturers agree on where the pedals are, so that’s something we can count on between cars.
It also means that certain layers can be updated, such as to improve performance or security, without having to upgrade the entire thing.
What are the four layers of TCP/IP
Datalink layer
The datalink layer (also called the link layer, network interface layer, or physical layer) is what handles the physical parts of sending and receiving data using the Ethernet cable, wireless network, network interface card, device driver in the computer, and so on.
Internet layer
The internet layer (also called the network layer) controls the movement of packets around the network.
Transport layer
The transport layer is what provides a reliable data connection between two devices. It divides the data in packets, acknowledges the packets that it has received from the other device, and makes sure that the other device acknowledges the packets it receives.
Application layer
The application layer is the group of applications that require network communication. This is what the user typically interacts with, such as email and messaging. Because the lower layers handle the details of communication, the applications don’t need to concern themselves with this.
Static IP address
Static IP addresses stay the same all the time. They are like the fixed address on your house, an unchanging address.
Dynamic IP address
When a computer system uses a dynamic IP address, it announces, “This is where you can find me!” to the local network – rather like the “address” of a hotel room, where the hotel knows how to find you.
Hyper-Text Transfer Protocol - HTTP
Used for: web services.
OSI Layer: Application Layer
A request-response protocol, HTTP gives users a way to interact with web resources such as HTML files by transmitting hypertext messages between clients and servers.
Which layers in the TCP/IP model maps to which in the OSI model?
The application layer of the TCP/IP model maps to the first three layers, i.e., application, session, and presentation layer of the OSI model.
The transport layer of the TCP maps directly to the transport layer of the OSI model.
The internet layer of the TCP/IP model maps directly to the network layer of the OSI model.
The datalink (link) layer of the TCP/IP model maps to the datalink and physical layer of the OSI model.
File Transfer Protocol - FTP
Used for: File transfers that does not require interaction. Faster than other protocols.
OSI Layer: Application Layer
A reliable, connection-oriented protocol that helps in the sequential transmission of data packets to ensure data reaches the destination on time without duplication.
User Datagram Protocol - UDP
Used for: broadcasts or multicast connections.
OSI Layer: Transport Layer
A communication protocol used across the Internet for especially time-sensitive transmissions such as video playback or DNS lookups. It speeds up communications by not formally establishing a connection before data is transferred.
Secure File Transfer Protocol - SFTP
Used for: File Transfers.
OSI Layer: Network Layer
SFTP, or Secure File Transfer Protocol, is a secure file transfer protocol that uses secure shell encryption to provide a high level of security for sending and receiving file transfers. SFTP is similar to FTPS in that it uses AES and other algorithms to secure data as it travels between different systems.
Network Security Protocols (SFTP, HTTPS, SSL)
These protocols ensure safe data transmission over the network connections. Network security protocols define the procedures to secure data from any unauthorized access. These protocols leverage encryption and cryptography to safeguard.
Hyper-Text Transfer Protocol Secure - HTTPS
Used for: Secure Web Browsing.
OSI Layer: Transport Layer
HTTPS is not a separate protocol from HTTP. Rather, it is a variant that uses Transport Layer Security (TLS)/Secure Sockets Layer (SSL) encryption over HTTP to secure communications.
When a web server and web browser talk to each other over HTTPS, they engage in what’s known as a handshake – an exchange of TLS/SSL certificates – to verify the provider’s identity and protect the user and their data.
It protects users against eavesdroppers and man-in-the-middle (MitM) attacks. It also protects legitimate domains from domain name system (DNS) spoofing attacks.
Post Office Protocol version 3 - POP3
used for: E-Mail clients.
OSI Layer: Application Layer
It provides access to an inbox stored in an email server. It executes the download and deletes operations for messages. Thus, when a POP3 client connects to the mail server, it retrieves all messages from the mailbox.
Simple Network Management Protocol - SNMP
Used for: monitoring & managing devices over the internet.
OSI Layer: Application Layer
An internet standard protocol used to monitor and manage network devices connected over an IP. SNMP is used for communication between routers, switches, firewalls, load balancers, servers, CCTV cameras, and wireless devices.
SNMP collects, organizes, and sends data from various devices for network monitoring assisting with fault identification and isolation. Both the monitored endpoints and the monitoring system rely on SNMP for seamless communication.
Address Resolution Protocol - ARP
Used for: establishing connections on a LAN
OSI Layer: Network Layer
ARP broadcasts a request packet to all the machines on the LAN and asks if any of the machines are using that particular IP address. When a machine recognizes the IP address as its own, it sends a reply so ARP can update the cache for future reference and proceed with the communication.
Border Gateway Protocol - BGP
Used for: routing data over the internet.
OSI Layer: Application Layer.
A set of rules that determine the best network routes for data transmission on the internet.
Transport Layer Security - TLS
Used for: secure browsing, messaging, file transfer.
OSI Layer: Application, Presentation, Session, and Transport.
TLS is an assymestric cryptographic protocol that provides end-to-end security of data sent between applications over the Internet. It is mostly familiar to users through its use in secure web browsing, and in particular the padlock icon that appears in web browsers when a secure session is established. However, it can and indeed should also be used for other applications such as e-mail, file transfers, video/audioconferencing, instant messaging and voice-over-IP, as well as Internet services such as DNS and NTP.
Difference between HTTPS & TLS
HTTPS (Hyper Text Transfer Protocol Secure) is the secure version of HTTP where communications are encrypted by SSL/TLS.
Internet Control Message Protocol - ICMP
Used for: detecting problems in transfer.
OSI Layer: Network Layer.
ICMP is a network protocol that devices use to warn about connectivity issues and errors. ICMP can notify devices that a forwarded message was too long or arrived out of order, and will issue an error message requesting that the device resend the content.
Point-To-Point - PPP
Used for: direct connections between endpoints.
OSI Layer: Data Link Layer.
Point-to-Point Protocol (PPP) is a TCP/IP protocol that is used to connect one computer system to another. Computers use PPP to communicate over the telephone network or the Internet.
IPv4/IPv6
Used for: IP-adressing for networks.
OSI Layer: Data Link
The IPv4 address is a 32-bit number that uniquely identifies a network interface on a machine. An IPv4 address is typically written in decimal digits, formatted as four 8-bit fields that are separated by periods.
Medium Access Control address - MAC
Used for: assigning a unique name to a device.
OSI Layer: Data Link
A MAC address (media access control address) is a 12-digit hexadecimal number assigned to each device connected to the network. Primarily specified as a unique identifier during device manufacturing, the MAC address is often found on a device’s network interface card (NIC).
Ethernet
Used for: LAN set ups. via cable.
OSI Layer: Data Link, Physical
Ethernet is the traditional technology for connecting devices in a wired local area network (LAN) or wide area network. It enables devices to communicate with each other via a protocol, which is a set of rules or common network language.
Wireless Application Protocol - WAP
Used for: WLANS and communication.
Wireless Application Protocol (WAP) is a specification for a set of communication protocols to standardize the way wireless devices, such as mobile phones and radio transceivers, can be used for internet access, including email, the web, newsgroups and instant messaging.
Network Basic Input/Output System - Netbios
Used for: Allowing computers to access shared resources over LAN
OSI Layer: Session Layer
The primary purpose of NetBIOS is to allow applications on separate computers to communicate and establish sessions to access shared resources, such as files and printers, and to find each other over a local area network (LAN).
Port
Used for: guiding communication to the right place.
OSI Layer: Session Layer
A port is a virtual point where network connections start and end. Ports are software-based and managed by a computer’s operating system. Each port is associated with a specific process or service.
OSI Layer 7 - Application
(Purpose, TCP/IP Layer, Devices, Troubleshoot)
Purpose: Interface (API)
TPC/IP Layer: Application
Devices: -
Troubleshoot: Wireshark
Human computer interaction layer, where applications can access network services.
OSI Layer 6 - Presentation
(Purpose, TCP/IP Layer, Devices, Troubleshoot)
Purpose: Formatting, Encryption, Compression.
TPC/IP Layer: Application
Devices: -
Troubleshoot: Wireshark
Ensures that data is in usable format. Also where data encryption occurs.
OSI Layer 5 - Session
(Purpose, TCP/IP Layer, Devices, Troubleshoot)
Purpose: Authentication and authorization.
TPC/IP Layer: Application.
Devices: Gateways
Troubleshoot: NSLOOKUP, NBTSTAT, Wireshark
Maintains connections and is responsible for controlling ports and sessions.
OSI Layer 4 - Transport
(Purpose, TCP/IP Layer, Devices, Troubleshoot)
Purpose: Reliability
TPC/IP Layer: Transport
Devices: Firewall
Troubleshoot: TELNET, NETSTAT, Wireshark
Transmits data using protocols (such as TCP/IP). Main purpose is reliability.
OSI Layer 3 - Network
(Purpose, TCP/IP Layer, Devices, Troubleshoot)
Purpose: Adressing, Routing
TPC/IP Layer: Internet
Devices: Router
Troubleshoot: IPCONFIG, PING, TRACERT, Wireshark
Decides which physical path the data will take
OSI Layer 2 - Data Link
(Purpose, TCP/IP Layer, Devices, Troubleshoot)
Purpose: Logical Link Control, Media Access Control
TPC/IP Layer: Link
Devices: Switch, Bridge, Access Point
Troubleshoot: Lights on device, ARP, Wireshark
Defines the format of the data on the network. MAC addresses.
OSI Layer 1 - Physical
(Purpose, TCP/IP Layer, Devices, Troubleshoot)
Purpose: Transmission
TPC/IP Layer: Link
Devices: Hub, NIC, Cable, Wireless
Troubleshoot: Lights on device
Transmits raw bit stream over the physical medium
Wide Area Network - WAN
wide-area network (WAN) is the technology that connects your offices, data centers, cloud applications, and cloud storage together. It is called a wide-area network because it spans beyond a single building or large campus to include multiple locations spread across a specific geographic area, or even the world.
Dynamic host-configuration protocol - DHCP
Used for: assigning IP addresses.
DHCP stands for dynamic host-configuration protocol, an IP-network protocol used for a server to automatically assign networked devices with IP addresses on the fly and and share other information to those devices so they can communicate efficiently with other endpoints.
Domain Name System - DNS
Used for: assigning IP to websites
The Domain Name System (DNS) resolves the common names of Web sites with their underlying IP addresses, adding efficiency and even security in the process.
Switch
Used for: guides packets sent through a network to the appropriate (physical) port.
A network switch is a device that operates at the Data Link layer of the OSI model — Layer 2. It takes in packets being sent by devices that are connected to its physical ports and sends them out again, but only through the ports that lead to the devices the packets are intended to reach. They can also operate at the network layer — Layer 3 where routing occurs.
Router
Used for: Directing traffic (traffic cop).
A router is a device like a switch that routes data packets based on their IP addresses. The router is mainly a Network Layer device. Routers normally connect LANs and WANs and have a dynamically updating routing table based on which they make decisions on routing the data packets. The router divides the broadcast domains of hosts connected through it.
Network Attached Storage - NAS
Used for: storage (like Egnyte)
Network-attached storage (NAS) is a category of file-level storage that’s connected to a network and enables data access and file sharing across a heterogeneous client and server environment.
Hypervisor
Used for: Allows for shared use of hardware (such as a server).
A hypervisor is software that separates a computer’s operating system and applications from the underlying physical hardware, allowing the hardware to be shared among multipe virtual machines.
Virtual machine - VM
Use for: Virtualization that allows a “safe” space to operate as it´s not connected to a physical machine.
A virtual machine (VM) is software that runs programs or applications without being tied to a physical machine. In a VM instance, one or more guest machines can run on a physical host computer.
Split tunneling
Used for: VPN functionality to separate traffic.
Split tunneling is a device configuration that ensures that only traffic destined for corporate resources go through the organization’s internet VPN, with the rest of the traffic going outside the VPN, directly to other sites on the internet.
Repeater
Used for: Ensure that signals don´t get to weak.
Its job is to regenerate the signal over the same network before the signal becomes too weak or corrupted to extend the length to which the signal can be transmitted over the same network. An important point to be noted about repeaters is that they not only amplify the signal but also regenerate it.
Hub
A hub is a basically multi-port repeater. A hub connects multiple wires coming from different branches, for example, the connector in star topology which connects different stations. Hubs cannot filter data, so data packets are sent to all connected devices.
Active Hub
Active Hub:- These are the hubs that have their power supply and can clean, boost, and relay the signal along with the network. It serves both as a repeater as well as a wiring center. These are used to extend the maximum distance between nodes.
Passive Hub
Passive Hub:- These are the hubs that collect wiring from nodes and power supply from the active hub. These hubs relay signals onto the network without cleaning and boosting them and can’t be used to extend the distance between nodes.
Bridge
A bridge is a repeater, with add on the functionality of filtering content by reading the MAC addresses of the source and destination. It is also used for interconnecting two LANs working on the same protocol.
Intelligent Hub
Intelligent Hub:- It works like an active hub and includes remote management capabilities. They also provide flexible data rates to network devices. It also enables an administrator to monitor the traffic passing through the hub and to configure each port in the hub.
Switch
A switch is a multiport bridge with a buffer and a design that can boost its efficiency (a large number of ports imply less traffic) and performance. A switch is a data link layer device. The switch can perform error checking before forwarding data, which makes it very efficient as it does not forward packets that have errors and forward good packets selectively to the correct port only.
Gateway
A gateway, as the name suggests, is a passage to connect two networks that may work upon different networking models. They work as messenger agents that take data from one system, interpret it, and transfer it to another system. Gateways are also called protocol converters and can operate at any network layer. Gateways are generally more complex than switches or routers. A gateway is also called a protocol converter.
Metropolitan Area Network - MAN
Larger area network that a LAN connects to.
Difference between Hub and Switch?
The basic difference between the two is when they receive information, network hubs broadcast the data to all connected devices, while switches identify the media access control (MAC) address in the data packet header to transmit the data only to the device that requested it.
Difference between a Router and Bridge?
The bridge connects two areas of the same network while the Router connects to an outside network.
Open Cloud
Public cloud is cloud computing that’s delivered via the internet and shared across organizations.
Private Cloud
Private cloud is cloud computing that is dedicated solely to your organization.
Hybrid Cloud
Hybrid cloud is any environment that uses both public and private clouds.
