Study notes covering Windows Client Network Management.
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| Term | Definition |
|---|---|
| Octet | A group of 8 bits in an IP address, separated by periods (e.g., 192.168.1.1 has 4 octets). |
| Subnet Mask | A 32-bit number used to divide an IP address into network and host portions (e.g., 255.255.255.0). |
| Public IP | An IP address assigned by an ISP that is routable on the internet. |
| Private IP | An IP address reserved for internal networks, not routable on the internet (e.g., 192.168.x.x). |
| APIPA | Automatic Private IP Addressing, 169.254.x.x range assigned when DHCP fails. |
| Loopback Address | 127.0.0.1, used for testing network functionality on the local machine. |
| Broadcast Address | An address that sends data to all hosts on a subnet (e.g., 192.168.1.255). |
| Network Address | The first address in a subnet, representing the network itself (e.g., 192.168.1.0/24). |
| Subnetting | Dividing a large network into smaller, more manageable subnets. |
| Fixed Length Subnet Mask (FLSM) | All subnets use the same subnet mask. |
| Variable-Length Subnet Mask (VLSM) | Allows subnets to use different subnet masks for efficient IP allocation. |
| Classless Inter-Domain Routing (CIDR) | A method of allocating IP addresses without relying on class-based rules. |
| ANDing | A logical operation used to determine the network address by combining IP and subnet mask. |
| Supernetting | Combining multiple networks into a larger address block, often used in route aggregation. |

Numbering Systems

Base 10

• Uses digits 0–9
• 10, 20, 30, 40 ... etc.
• Standard numbering system we use daily.

Binary

• Base-2 system.
• Uses 1s and 0s (bits).
• Represents states such as ON (1) and OFF (0).

Hexadecimal

• Base-16 numbering system.
• Digits: 0–9 and letters A–F.
• 4 bits = 1 nibble.
• Commonly used in MAC addresses.
• After 9 comes A (10), B (11), C (12), D (13), E (14), F (15).

Binary to Decimal Conversion

• 2^0 = 1
• 2^3 = 8
• 2^6 = 64
• 2^7 = 128

• Total = 170

Binary to Hexadecimal

• 4 bits = 1 hex digit.
• Example: 1010 in binary = A in hex.

What’s an IP?

• IP address = 4 octets (e.g., 192.168.1.42).
• Written in dotted decimal format.
• 255.255.255.255 = all bits set to 1.
• Subnet range excludes:
  • Network Address (first address).
  • Broadcast Address (last address).
• Gateway is often the first usable IP after the network address.

Public vs. Private IP

• Public IP: Identifies your router to the outside world.
• Private IP: Used inside local networks.
• NAT (Network Address Translation): Converts private IPs to a public IP for internet access.

Subnets

• Subnet = A smaller logical network inside a larger one.
• Subnet Mask = Separates network ID from host ID.
• Example:
  • IP: 192.168.1.42
  • Subnet Mask: 255.255.255.0
  • Network ID: 192.168.1.0
  • Host ID: 42

Bogon IPv4 Addresses

• 0.0.0.0/8 – This network
• 10.0.0.0/8 – Private IPv4 block
• 100.64.0.0/10 – Carrier-Grade NAT
• 127.0.0.0/8 – Loopback
• 127.0.53.53 – Name collision occurrence
• 169.254.0.0/16 – APIPA (link-local)
• 192.0.0.0/24 – IETF protocol assignments
• 192.0.2.0/24 – TEST-NET-1
• 192.168.0.0/16 – Private IPv4 block
• 192.18.0.0/15 – Benchmark testing
• 198.51.100.0/24 – TEST-NET-2
• 203.0.113.0/24 – TEST-NET-3
• 224.0.0.0/4 – Multicast
• 240.0.0.0/4 – Reserved
• 255.255.255.255/32 – Limited broadcast

IPv4 Classes

• Class A: 0.0.0.0 – 127.255.255.255
• Class B: 128.0.0.0 – 191.255.255.255
• Class C: 192.0.0.0 – 223.255.255.255
• Class D: 224.0.0.0 – 239.255.255.255 (Multicast)
• Class E: 240.0.0.0 – 255.255.255.255 (Experimental)

DHCP (Dynamic Host Configuration Protocol)

• Automatically assigns IP addresses.
• Usually runs on a router or server.
• Scope defines:
  • Range of IPs.
  • Subnet mask.
  • Default gateway.
  • DNS server.

DORA Process

1. Discover – Client searches for DHCP server.
2. Offer – DHCP server offers an IP.
3. Request – Client requests the offered IP.
4. Acknowledge – DHCP server confirms lease.

Ping

• Utility used to test network connectivity.
• Uses ICMP echo requests/replies.

IPv6

• 128-bit addressing, written in hex.
• Approx. 340 undecillion addresses.
• Consecutive zeros can be shortened using ::.
• Loopback address: ::1/128.

Virtual Private Networks (VPNs)

• Encrypted communication over the internet.
• Provides privacy, security, and anonymity.

VPN Types

• Remote Access VPN
• Site-to-Site VPN
• VPN Applications

VPN Protocols

• PPTP – Legacy, insecure, 128-bit encryption, TCP 1723.
• L2TP/IPsec – Stronger, uses UDP 500, TCP 1701.
• GRE – Tunneling, used by Cisco, requires IPsec for security.
• OpenVPN – Open-source, industry standard, AES-256.

Wireless

Wireless Standards

• 802.11 (1997) – 1–2 Mbps, 2.4 GHz.
• Wi-Fi 1 (802.11b, 1999) – 1–11 Mbps, 2.4 GHz.
• Wi-Fi 2 (802.11a, 1999) – 6–54 Mbps, 5 GHz.
• Wi-Fi 3 (802.11g, 2003) – 6–54 Mbps, 2.4 GHz.
• Wi-Fi 4 (802.11n, 2009) – 6.5–600 Mbps, 2.4/5 GHz.
• Wi-Fi 5 (802.11ac, 2013) – Up to 6.9 Gbps, 5 GHz.
• Wi-Fi 6 (802.11ax, 2021) – Up to 9.6 Gbps, 2.4/5 GHz.
• Wi-Fi 6E (802.11ax, 2021) – Wi-Fi 6 on 6 GHz band.
• Wi-Fi 7 (802.11be, 2024) – Up to 23 Gbps, 2.4/5/6 GHz.
• Wi-Fi 8 (802.11bn, TBD) – Future, very high capacity.

Frequency Bands

• 2.4 GHz – Channels 1–14, only 1/6/11 are non-overlapping.
• 5 GHz – 24 non-overlapping channels, faster, less interference.
• 6 GHz – Higher capacity, reduced interference.

Wireless Enhancements

• MIMO – Multiple antennas increase throughput.
• MU-MIMO – Access point can serve multiple devices simultaneously.
• Channel Bonding – Combines two channels for more bandwidth.
• 802.1X – Secure authentication method.

Wireless Security

• WPS – One-button setup, insecure (disable it).
• RADIUS (802.1X) – Centralized authentication, authorization, accounting.
• WEP – Weak, deprecated.
• WPA (2003) – Improved over WEP.
• WPA2 (2004) – Strong security, AES recommended.
  • WPA2-Personal: Pre-shared key (8–63 characters).
• WPA3 (2018) – Strongest, uses SAE handshake, 192-bit encryption.

Encryption

• TKIP – Legacy, insecure, replaced by AES.
• AES – Strong encryption standard.
  • AES-128 → 10 rounds.
  • AES-192 → 12 rounds.
  • AES-256 → 14 rounds.