CS-iGCSE-CIE-Notes
Network Hardware**
NIC | 3.4.2
A NIC (network interface card) is necessary for a device to connect to the internet. It is typically in the device’s hardware. Additionally, **it contains the MAC address assigned by the manufacturer. If the NIC changes, the MAC address will also be changed.**It is usually connected to a network cable. A wireless NIC or WNIC does this with microwaves. 
MAC Addresses | 3.4.2
A MAC (Media Access Control) address is the **unique number assigned by the manufacturer to any device that accesses the internet. It is a method of identifying the device. MAC addresses are static.**The first half identifies the manufacturer of the device: NThe second half is the serial number allocated to the device: DIt is 48 bits long and is identified by:12 digits of 6 hexadecimal pairs: NN-NN-NN-DD-DD-DD**Types of MAC addresses:* UAA (Universally administered address)
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The unique address is given to the physical device by the manufacturer
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This is rarely changed
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LAA (Locally administered address)
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This can override the UAA and is assigned by a network administrator or special software
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May be necessary as:
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Some systems have strict requirements on MAC addresses and the UAA must be changed
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Needs to bypass a filter on a router or firewall
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Bypass network restrictionsLAAs are relatively easy to get however it’s risky as it must be a unique address.**
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IP addresses | 3.4.3
IP (Internet protocol) - a numeric address that identifies any device on a network so that data can be sent to accordingly. When a device connects to a private network, a private IP address unique to that network is assigned by a router. This may be the same address as another device on a separate network. When a router connects to a public network, a public IP assigned by an ISP (internet service provider) is given to the router, and all devices connected to that router share that IP address. This IP is different to every other IP address on the internet. Header format of a datagram or packetFunction is to improve efficiencyIPv4 - **32-bit system (4 groups of 8 bits), not enough unique addresses for every device on the planet, only 4 billion address available, it appears in denary form: 254.25.28.77IPv6 - 128-bit system allowing for billions and billions of unique addresses for each person, eight groups of hexadecimal digits: A8FB:7A88:FFF0:0FFF:3D21:2085:66FB:F0FA**IPv6 addresses not only allow more IP addresses to be used, but due to their formatting they allow more efficient packet routes, reduces risk of collision, and has built-in authentication checks.**Static vs dynamic IP addressesIP addresses are digital addresses that help devices connect to the internet. There are two types of IP addresses: static and dynamic. The main difference between them is that static addresses don’t change, and dynamic addresses are temporary and change overtime. They are both assigned by an ISP (Internet Service Provider) or router.**A static IP address is a fixed address that is assigned to a device and does not change. It is typically used for servers, printers or other devices that need to have a consistent address on the internet. Static IP addresses are also required when websites need to remember your IP address. On the other hand, a dynamic IP address is assigned to a device temporarily by a service provider or a router. This IP address changes overtime and is recycled for use by other devices. They’re usually used for personal devices like laptops, smartphones, and gaming consoles. Dynamic IP addresses are much easier to manage than static addresses; they don’t require any configuration and the provider assigns the next available address. On top of this, they’re more secure and the device has greater privacy.Everytime a device logs onto the internet, it requests a temporary IP address from a **Dynamic Host Configuration Protocol (DHCP). This can also be done by a router. It selects an IP address from a pool when a computer requests one as routers can act as simple DHCP servers. **
Routers | 3.4.4
Routers direct data packets between different networks and to their destinations. They allow networks to communicate by converting data from one network to a different protocol that another network understands.When handling data packets, the router looks at the IP address and MAC address of the destination and sends the packet to the right switch to be sent to the correct network. Every computer in one network shares a part of their IP addresses which is how the router knows which switch to send data to. Routers can also act as proxy servers to protect devices from network traffic. Routers can have an internal DNS (domain name server) and DHCP (Dynamic host configuration protocol)DHCP is a network protocol that manages a collection of unique IP addresses and assigns them to devices when they connect to a network. This is how routers assign IP addresses. All computers under the same network are connected to a network switch. There can be multiple switches on a network. If the switch cannot find a matching MAC address connected to it, it will send the data to another switch on the same network until the correct destination is found. (picture on the left is an example of a network switch where every device on a network is connected to its switch)
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