Coconote
AI notes
AI voice & video notes
Export note
Try for free
Understanding IP Subnetting and Masks
Aug 6, 2024
Lecture on IP Subnetting and Subnet Masks
Introduction
Understanding subnet masks is crucial in learning IP subnetting.
Differences between Class A, Class B, and Class C IP subnets are often discussed.
Classful subnetting architecture is outdated since 1993, today we use classless subnetting.
Reviewing classful subnetting helps in understanding modern subnetting.
IP Address Classes
Five Classes
: A, B, C, D, E
Class A
: 1-127 (for workstations)
Class B
: 128-191 (for workstations)
Class C
: 192-223 (for workstations)
Class D
: 224-239 (for multicast)
Class E
: 240-254 (reserved, not used in production)
Determining IP Address Class
Class A
: First octet 1-127
Class B
: First octet 128-191
Class C
: First octet 192-223
Class D
: First octet 224-239 (multicast)
Class E
: First octet 240-254 (reserved)
Binary Conversion
: First four bits help to determine the class
0xxx: Class A
10xx: Class B
110x: Class C
1110: Class D
1111: Class E
Default Subnet Masks
Class A
: 255.0.0.0
Class B
: 255.255.0.0
Class C
: 255.255.255.0
Class D and E
: Not used for subnetting
Practical Examples
Example 1
: IP Address 17.22.90.7
Class A
Network Address: 17.0.0.0
First Usable Host: 17.0.0.1
Broadcast Address: 17.255.255.255
Last Usable Host: 17.255.255.254
Example 2
: IP Address 220.10.77.40
Class C
Network Address: 220.10.77.0
First Usable Host: 220.10.77.1
Broadcast Address: 220.10.77.255
Last Usable Host: 220.10.77.254
Example 3
: IP Address 165.245.0.1
Class B
Network Address: 165.245.0.0
First Usable Host: 165.245.0.1
Broadcast Address: 165.245.255.255
Last Usable Host: 165.245.255.254
Calculating Key Values
Network Address
: First IP in a subnet, set all host bits to 0
First Usable Host Address
: Network address + 1
Broadcast Address
: Last IP in a subnet, set all host bits to 1
Last Usable Host Address
: Broadcast address - 1
Advanced Examples
Example 1
: IP Address 10.74.222.11 (Class A)
Network Address: 10.0.0.0
First Usable Host: 10.0.0.1
Broadcast Address: 10.255.255.255
Last Usable Host: 10.255.255.254
Example 2
: IP Address 172.16.88.200 (Class B)
Network Address: 172.16.0.0
First Usable Host: 172.16.0.1
Broadcast Address: 172.16.255.255
Last Usable Host: 172.16.255.254
Example 3
: IP Address 192.168.4.77 (Class C)
Network Address: 192.168.4.0
First Usable Host: 192.168.4.1
Broadcast Address: 192.168.4.255
Last Usable Host: 192.168.4.254
Conclusion
These calculations are simpler with classful subnetting but modern networks use classless subnetting.
Future lessons will cover classless subnetting calculations.
📄
Full transcript