1. Basics of Networking

NETWORK — Collection of computers and devices connected together for communication & data exchange between them.
NODES — Devices connected to the Network. Includes computers, servers, printers, routers
Protocols — Set of rules and standards how data is transfer over network like TCP,HTTP,FTP
LAN (LOCAL AREA NETWORK) — Network that covers a very small area
WAN (WIDE AREA NETWORK) — Network that covers a wide area like city, country.
IP Address — Unique Numerical Id for every device on network
Firewall — Monitor and control the inbound and outbound network traffic

2. IPv4 and Subnetting

IPv4 = Internet Protocol version 4

It uses 32 bit address. It has both public and private IP’s. Starts from 0.0.0.0 to 255.255.255.255 approx 4 billion ip address. Inthat 18million address are private.

10.0.0.0 — 10.255.255.255 — (24 bit) Class A — 1,67,77,216

172.16.0.0 — 172.31.255.255 — (20 bit) Class B — 10,48,576

192.168.0.0 — 192.168.255.255 — (16 bit) Class C — 65,536

Subnetting

It’s a Network Security Device that monitors and filters inbound and outbound network traffic.
Firewall is the first line of defence in network security.
It can be Hardware, Software, Software as a Service (SaaS), Public Cloud , Private Cloud (virtual)

TYPES OF FIREWALL

PROXY FIREWALL — Filter network in Application layer ,Gateway from one network to another.
PACKET FILTERING — Control data flow
STATEFUL INSPECTION — Allow or Block Network traffic based on state,port and protocol
Next Generation Firewall — Deep pocket Inspection, intrustion prevention
UTM (Unified Threat Management) — Capabilities of stateful inspection, Intrustion Prevention and antivirus in a loosely linked manner
Thread Focused — Advanced Threat detection.

INBOUND — Protect Network against incoming traffic

OUTBOUND — Project against outgoing traffic

Domain Name System (DNS) is the Phonebook of the Internet
Four servers work together to deliver IP address to the Client
DNS Caching — The recursive resolver store the information for a limited amount of time. Meantime host hit the same server instead of doing the domain lookup process, simply respond to the client instantly

DNS LOOKUP

Cloud Flare — Its a large network of servers that can improve the Security, Performance and Reliability of anything connected to the Internet. Cloud flare is the Content Delivery Network by providing Edge locations.
Performance Improved by providing the Edge Locations. Example: If a cloud flare customer’s server is in USA, if the client access the server in Europe cloud flare provides their servers to reach the client without latency

Provides Information about a domain including what IP address is associated with the domain. DNS Records also have TTL (Time to Live) defines how often DNS Server clear the records

TYPES OF DNS RECORD:

Network Access Control — Only Authenticated and trusted endpoint devices can get into the system.
Firewall Security — Monitor and filters the incoming and outgoing network traffic. It follows defined rules of IP address and ports to allow or deny traffic
Intrusion Prevention System (IPS) — Identify and Prevent unusual network traffic. Its does not follow any static rules like firewall but actively analyze, learn and create rules. EXAMPLE: If Firewall is your Building Security Gate, IPS is like your security guard behind the gate
Security Information and Event Management (SIEM) -It sends out reports on security-related events like failed logins and sends out alerts if its analysis indicates a potential security issue