DNS, DHCP, SSH, Proxy, HTTP, Email, FTP, and IRC Explained
Understanding Key Internet Protocols
DNS (Domain Name System) translates domain names to IP addresses, locating websites. Examples of domain extensions include:
- .com – Commercial
- .org – Organization
- .edu – Educational
- .net – Internet and communications
- .gov – Governmental organizations
Domain delegation decentralizes DNS database administration. Reverse resolution returns a hostname given an IP address.
DHCP (Dynamic Host Configuration Protocol)
DHCP offers fast network configuration to clients. Allocation
Read MoreTCP and UDP: Network Communication Protocols
TCP and UDP: Key Differences
UDP (User Datagram Protocol)
- Data-oriented
- Unreliable, connectionless
- Simple
- Supports Unicast and Multicast
- Used by SNMP
TCP (Transmission Control Protocol)
- Stream-oriented
- Reliable, connection-oriented
- Complex
- Unicast only
- Common Use Cases:
- Used by most Internet applications
- Web (HTTP)
- Email (SMTP)
Fragmentation
DF (Don’t Fragment):
- 1: Don’t Fragment
- 0: Could Fragment
MF (More Fragment):
- 1: More fragmentation needed
- 0: No more fragmentation needed, last fragment.
All fragments of one packet
Read MoreTCP Protocol: Exercises, Flow Control, Congestion & Error Management
TCP Protocol: Exercises and Mechanisms
TCP Exercise 1: Suppose a TCP connection is transferring a file of 5000 bytes. The first byte is numbered 10001. What are the sequence numbers for each segment if data is sent in five segments, each carrying 1000 bytes?
The following shows the sequence number for each segment:
- Segment 1 ➡ Sequence Number: 10,001 (range: 10,001 to 11,000)
- Segment 2 ➡ Sequence Number: 11,001 (range: 11,001 to 12,000)
- Segment 3 ➡ Sequence Number: 12,001 (range: 12,001 to 13,000)
Digital Signatures, OSI Model, and Network Attacks
Digital Signatures and Encryption
Digital Signature: A cryptographic method that ensures the identity of the sender in messages and documents. It uses two keys: a public key (Kp) and a secret key (Ks). The message is signed using the private key: F(M, Ks) = S
PGP (Pretty Good Privacy)
A system used for encryption and decryption to protect information that travels over the internet (including email) and other files (such as those stored on a hard drive). The system is based on public-key cryptography.
Read MoreNetworking Fundamentals: Ethernet, IP, VLANs, and More
Topic 2: The 802 Project and Ethernet Standards
The 802 project, supported by ISO, divides the data link layer into two sublayers: Logical Link Control (LLC) and Media Access Control (MAC). It defines the specific aspects of each local area network.
Main Features of Ethernet Standards:
- 10BASE5: Uses 500m of coaxial cable (50 ohm) with PCs connected every 2.5m.
- 10BASE2: Uses 185m of coaxial cable (50 ohm) with a maximum of 30 PCs and BNC connectors.
- 10BASET: Uses twisted pair cables with hubs and switches.
DHCP and SSH Services: Configuration, Security, and Encryption
DHCP Service Explained
Item 8. What is the DHCP service? Dynamic Host Configuration Protocol (DHCP) offers fast network configuration for clients. The administrator can assign dynamic IP addresses to clients through the DHCP server, without requiring manual configuration of IP, subnet mask, gateway, etc. The DHCP protocol uses UDP ports 67 and 68 for communication between server and client.
The DHCP server can automatically configure:
- Client IP address
- Subnet Mask
- Lease time
- Renewal time
- Rebinding time
DHCP
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