Overview of topics that will be covered in this series
A core understanding about the concepts of Computer Network is essential for any IT professional. This series will cover the following topics
| Topic | Description |
|---|---|
| OSI Model - | |
| Application Layer - | |
| Presentation Layer - | |
| Session Layer - | |
| Transport Layer - | |
| Network Layer - | |
| Data Link Layer - | |
| Physical Layer - | |
| TCP - | |
| UDP - | |
| IP Addressing - | |
| Subnetting - | |
| Supernetting - | |
| Ping - | |
| Trace Route - | |
| nslookup - | |
| FTP/TFTP/SFTP - | |
| Telnet - | |
| SMTP - | |
| SNMP - | |
| ICMP - | |
| Checksum - | |
| CRC - | |
| Flow Control - | |
| Congestion Control - | |
| Error Detection - | |
| Error Correction - | |
| TCP Header - | |
| UDP Header - | |
| IP Header - | |
| Frame Header - | |
| Logical Link Control - | |
| Media Access Control - | |
| Ethernet - | |
| Sequence Number - | |
| Acknowledgement Number - | |
| Sliding Window Protocol - | |
| ARP/RARP - | |
| NAT - | |
| DHCP - | |
| DNS - | |
| Hub - | |
| Switch - | |
| Bridge - | |
| Router - | |
| Gateway - | |
| Subnet Mask - | |
| Public Vs Private IP Address - | |
| MAC Address - |
Questions with answers
What is ARP and why is it important in routing?
ARP (Address Resolution Protocol) is crucial for routing because:
- It maps IP addresses to MAC addresses in local networks.
- Enables devices to communicate on the data link layer.
- Allows routers to forward packets to the correct destination.
- Maintains an ARP cache for efficient address resolution.
- Essential for proper functioning of IP networks.
Follow up question
Which layer of the OSI model does ARP operate on?
- ARP operates on the data link layer (Layer 2) of the OSI model.
What is proxy ARP? Why is the term proxy used here?
Proxy ARP is:
- A technique where a device answers ARP requests on behalf of another.
- Usually implemented by routers to facilitate communication between subnets.
- “Proxy” refers to the router acting as an intermediary or representative.
- It responds with its own MAC address for IP addresses it can route to.
- Helps in scenarios where devices can’t directly communicate due to network segmentation.
Follow up question
How does proxy ARP differ from traditional ARP?
- Proxy ARP is used for routing between networks, while ARP is for local address resolution.
- Proxy ARP responds with its own MAC address, while ARP responds with the target’s MAC address.
Why is sequence numbering in TCP essential?
Sequence numbering in TCP is essential because:
- It ensures data is delivered in the correct order.
- Allows for detection of lost or duplicate packets.
- Enables reliable data reassembly at the receiving end.
- Facilitates efficient retransmission of lost segments.
- Helps manage flow control and congestion control mechanisms.
Follow up question
How does TCP use sequence numbers to handle out-of-order packets?
- TCP uses sequence numbers to reorder out-of-order packets at the receiving end.
- It buffers incoming packets until all preceding segments are received, then delivers them in the correct order.
Why do we need IP address when the MAC address is unique? Can’t we communicate only with MAC address?
We need IP addresses alongside MAC addresses because:
- MAC addresses are only meaningful within a local network.
- IP addresses enable global routing across different networks.
- IP provides a hierarchical addressing scheme for efficient routing.
- MAC addresses don’t scale for internet-wide communication.
- IP allows for logical network organization independent of hardware.
Follow up question
How does ARP help bridge the gap between IP and MAC addresses?
- ARP resolves IP addresses to MAC addresses for local network communication.
- It enables devices to communicate using IP addresses while handling the underlying MAC addressing.
- ARP is essential for routing packets between IP networks based on MAC addresses.
- ARP maintains a mapping table (ARP cache) for efficient address resolution.