Week #9 - Highyeena/Tech-Journal GitHub Wiki
Networking
Network Types
- Personal Area Network (PAN) = personal devices that communicate in close proximity (wired or unwired). Ex. Bluetooth speakers connected to a phone
- Local Area Network (LAN) = group of devices that share resources in a small area (such as a room/building). Ex. Ethernet; networked classroom
- Metropolitan Area Network (MAN) = Connects between different sites in a city (connects multiple LANs). Ex. Connected college campuses
- Wide Area Network (WAN) = Connects LANs on a large scale. Ex. company buildings being connected in two remote locations
- Wireless LAN (WLAN) = wireless network with an access point and devices that connect to it.
- Wireless WAN (WWAN) = Wireless connection on a large scale (uses a mix of technology like cellular)
- Wireless Mesh Network (WMN) = passes data between peer radio devices and can be used over long distances (used in emergency situations)
Network Topologies
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Network Topology = How a network is wired
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Ethernet = common type of LAN; Every device is connected to a central device (Switches > Hubs)
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Hubs can cause collisions as two devices try to place data onto the network at the same time (causes a delay in sending data for a period of time; switches don't have this problem)
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Managed Switch = Has an IP address assigned. Can be configured, modified, and monitored through a corporate network.
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Unmanaged Switch = connects devices to form a network. Used in home or small business's wired networks.
OSI Model
- Each layer uses the layer below it and provides a function to the layer above it (cannot use a layer without using the ones below it first)
- Application (Data) = Provides Network Services to software applications on the network (Firewalls operate here)
- Presentation (Data) = Translates data from one character set to another
- Session (Data) = Manages the communication and synchronization between network devices
- Transport (Segments) = Provides the mechanisms for how data is sent (Ex. error correction)
- Network (Packets) = Provides path selection between two networks. (Routers are at this layer and send data toward the destination network)
- Data Link (Frames) = Encapsulates bits into frames. Provides error control (MAC addresses operate here)
- Physical (bits) = Defines how bits are transferred and received. Defines the network media, connectors, and voltage levels
TCP/IP Model
- TCP/IP Model is the most common network protocol and is required to access the internet
- Application (Data) = TCP/IP-based protocol; equivalent to layers 7-5 on the OSI Model (Ex. HTTP, DNS, HTTPS)
- Transport (Segment) = add port numbers in the header so the computer can identify which application sends the data. Returning Data contains port numbers to determine which window the data will go into
- Internet (Packet) = adds a source and destination IP address to identify the source and destination network devices
- Network Access (Frame/Bits) = Defines how to format the data for the type of network used (Ex. If Ethernet is used, uses an Ethernet header)
Network Addressing
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Network adapters have two types of addresses: MAC address and IP address
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MAC address = 46 bit number burned into a chip (represented by a hexadecimal). First 24 bits represent the manufacturer
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IP address (IPv4) = most common on LANs. 32-bit number that is entered into a NIC's config parameters. Used when multiple networks are connected + accessing the internet
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IP address (IPv6) = used by corporate devices or ISPs. 128 bit length. Computers have both an IPv4 and IPv6 address assigned.
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IPv4 addresses are grouped in 5 classes: A, B, C, D, E
- Class A, B, C are used by network devices
- Class D addresses are used for multicasting (sending data to a group of devices)
- Class E addresses are used for experimentation
Network Troubleshooting
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"ping" command = used to check connectivity around the network
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First sign of network issues = unavailable resources (such as internet or local resources in a company network)
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"ipconfig" command = used to see both wired and wireless NICs (can be used if a network device does not get an IP address properly from a server)
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"tracert" command = displays the path a packet takes through the network (identifies faults in a larger network + shows network latency)
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"nslookup" command (for DNS servers) = displays domain names and their associated IP addresses
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"net" command = used to manage the entire network (displays other options for use with net)