Question

What is the network address if given this IP address and the following subnet mask?  Please note that the network may be different if the subnet mask is different.

IP address 178.47.188.176

1. 255.255.255.0     network 178.47.188.0
2. 255.255.255.240 network 178.47.188.176
3. 255.255.0.0          network 178.47.0.0
4. 255.255.240.0      network 178.47.176.0

How many total/useable hosts?

1a. /20    Total_______________          Useable_______________

1b. /21    Total_______________          Useable_______________

1c. /28    Total_______________          Useable_______________

1d.  /27     Total_______________          Useable_______________

1e. /30     Total_______________          Useable_______________

Answer 1

Answer)

Total number of hosts = 2^{number of zeros} Usable Hosts = 2^{number of zeros} - 2

1a. 178.47.188.176/20

11111111.11111111.11110000.00000000

Hosts: Total = 2¹² = 4096 Useable = 4096 - 2 = 4094

1b. 178.47.188.176/21

11111111.11111111.11111000.00000000

Hosts: Total = 2¹¹ = 2048 Useable = 2048 - 2 = 2046

1c. 178.47.188.176/28

11111111.11111111.11111111.11110000

Hosts: Total = 2⁴ = 16 Useable = 16 - 2 = 14

1d. 178.47.188.176/27

11111111.11111111.11111111.11100000

Hosts: Total = 2⁵ = 32 Useable = 32 - 2 = 30

1e. 178.47.188.176/30

11111111.11111111.11111111.11111100

Hosts: Total = 2⁵ = 32 Useable = 32 - 2 = 30