test 2

VPN (VIRTUAL PRIVATE NETWORK)

 Extension of private network over a public network. It doesn't necessarily imply on encryption, but it uses encryption.  test

IMPORTANT

 Hits To Remember:

• Intranet - Communication within the same autonomous system
• Internet - Communication between different autonomous system     

• Broadcast/Multicast: One to All and One to Many

• IPV4/IPV6: IANA (Internet Assigned Numbers Authority) manages the global pool of IPv4 addresses and allocates large blocks to Regional Internet Registries (RIRs), which then distribute them to ISPs and organizations.

•  Public IP: A public IP address is a globally unique IP address assigned by an Internet Service Provider (ISP), and it is accessible over the internet.

            Example public IPs:
        8.8.8.8 (Google DNS)
        142.250.190.14 (Google server)
        52.95.110.1 (AWS server)

• Private IP: A private IP address is an IPv4 address reserved for communication within a local area network (LAN). It is used exclusively for internal communication between devices.

Private IP Address Ranges (IPv4):

Type	IP Range	CIDR Notation	Example IPs	Purpose
Class A	10.0.0.0 – 10.255.255.255	10.0.0.0/8	10.0.0.1, 10.1.1.5	Internal LAN use
Class B	172.16.0.0 – 172.31.255.255	172.16.0.0/12	172.16.5.10, 172.20.1.1	Internal LAN use
Class C	192.168.0.0 – 192.168.255.255	192.168.0.0/16	192.168.1.1, 192.168.100.5	Internal LAN use
Loopback	127.0.0.0 – 127.255.255.255	127.0.0.0/8	127.0.0.1	Device internal testing
Multicast	224.0.0.0 – 239.255.255.255	224.0.0.0/4	224.0.0.1, 239.255.255.255	Group communication (multicast)
APIPA	169.254.0.1 – 169.254.255.254	169.254.0.0/16	169.254.0.1, 169.254.10.10	Auto IP when DHCP fails (link-local)

• Application Layer  - This layer interacts directly with the user.

           HTTP , https,ftp,smtp,dns,dhcp,RIP,BGP,tftp,telnet,ssh

                                                  

• Switch/Router:                                                                                                                                              

Feature	Switch	Router
Function	Connects devices within a LAN	Connects different networks (e.g., LAN to WAN)
Layer of OSI Model	Layer 2 (Data Link Layer) Some at Layer 3	Layer 3 (Network Layer)
Uses	MAC addresses	IP addresses
Data Forwarding	Within the same network	Between different networks
Device Communication	Device-to-device within the same network	Between different networks and internet
Main Role	Network expansion within LAN	Routing traffic to/from other networks
IP Address Assignment	No (unless Layer 3 switch)	Yes (via DHCP)
Security Features	Basic (VLAN, port security)	Advanced (NAT, firewall, ACL)
Internet Access	Cannot provide	Can provide
Common Use	Offices, LANs, data centers	Homes, offices, ISPs (to connect to internet)

•  TCP/UDP:                     

Feature TCP (Transmission Control Protocol) UDP (User Datagram Protocol) Connection Connection-oriented (establishes a connection) Connectionless (no connection needed) Reliability Reliable (ensures all data is received) Unreliable (no guarantee of delivery) Error Checking Yes, with acknowledgment and retransmission Yes, but no retransmission Data Order Guarantees data is received in correct order No guarantee of order Speed Slower due to overhead of connection and checks Faster due to minimal overhead Overhead High (more control information) Low (lighter, simpler) Use Cases Web browsing (HTTP/HTTPS), email (SMTP), file transfer (FTP) Streaming, gaming, VoIP, DNS, real-time apps Header Size 20–60 bytes 8 bytes Flow Control Yes No Congestion Control Yes No Acknowledgments Yes No No

• ARP (ADDRESS RESOLUTION PROTOCOL) -  To find destination MAC address using destination IP address, It correlates between layer 2 and layer 3.                                                      ( It is a Layer 2 protocol encapsulated in Ethernet 2 frame).- arp -a                                                   Types of arp : Reverse ARP, Proxy ARP and GRAP.

1. RARP : Rarp is used to resolve ip address using mac address. Used before DHCP and RARP Server provides only IP address.
2.    Proxy ARP  is a process, where the routers default gateway replies with its own MAC address on behalf of the destination device when the source is trying to reach an IP in another subnet. It allows devices on different subnets to communicate without reconfiguring their subnet mask or gateway.

3. GARP : Grap used to avoid ip conflicts, where the source and target ip will be same. It is used in high availability protocols like VRRP(Virtual Router Redundancy Protocol)           

                                                                                               

• How to Find MAC address:             

            In phone - settings - About phone - detailed info/specs - status

            In system - press Windows key + R, In command prompt - Run cmd = ipconfig/all

• VPN (Virtual Private Network) - Extension of private network over a public network. It doesn't necessarily imply on encryption, but it uses encryption.

• NAT (Network Address Translation), which translates private IPs to a public IP
  

SUBNETTING

 FORMULA TO FIND THE BLOCK SIZE : 

Host: Represents no. of users in the network

To find no of users:  2^h-2  >= User Requirement 

To find Host Bit (h):  32 - CIDR value

Subnet: A logical subdivision of an IP network

To find subnets:  2^(CIDR Value - Bit value of the given class)

Subnet bit/CIDR value: Classless Inter-Domain Routing - Current number of network bits

To find CIDR Value(subnet bit): Total value of octet i.e. 32 - Host bit value

Subnet Mask: It is used to differentiate host bit and network bits in an ip address

by CIDR value 

Network bits are represented as  1 and Host bits are represented as 0.

To find Subnet mask: Exclude the host bit value from the octet value from right to left and add the remaining bit values

Wildcard Mask: It is the reverse of subnet Mask

To find Wildcard mark: 255-SM

Network bits are represented as  0 and Host bits are represented as 1.

                                          

 

Make It Simple Networking

Make It Simple Networking 

TFTP

MAC ADDRESS

MAC ADDRESS: MEDIA ACCESS CONTROLLER

      It is a 48 bit hexadecimal value, assigned to a network interface controller (NIC) /

      network card / Ethernet card / Wi-Fi card.

      It is a physical address in communications within a network segment .

First 24 bits OUI (Organizationally Unique Identifier)/ Last 24 bits NIC-specific

Least Significant bit of the most significant byte

8th bit (LSB)	I/G (Individual/Group) → 0 = Unicast (one-to-one), 1 = Multicast/Broadcast
7th bit	U/L (Universal/Local) → 0 = Globally unique (from manufacturer), 1 = Locally administered (manually changed / overridden)

 

How to Find MAC address:             

            In phone - settings - About phone - detailed info/specs – status

            In system - press Windows key + R, In command prompt - Run cmd = ipconfig/all