lab 18
Problem 1:
Ask yourself “What Class is this?” This is a Class C network with a default subnet mask of 255.255.255.0.
Therefore, your reference point is /24. Anything over /24 represents the number of bits borrowed from the fourth octet.
This is how your custom subnet mask looks in binary form: 11111111 11111111 11111111 11100000.
a. Custom Subnet Mask: 255.255.255.224
b. Bits Borrowed: 3
c. Number of subnets: 8
d. Magic number: 32
e. Number of valid hosts per subnet: 30
f. (Sub) network address of subnet 0: 192.168.10.0
g. First usable host address in subnet 0: 192.168.10.1
h. Last usable host address in subnet 0: 192.168.10.30
i. Broadcast address in subnet 0: 192.168.10.31
j. (Sub) Network address in subnet 3: 192.168.10.96
k. Last usable host address in subnet 4: 192.168.10.158
Subnet
Subnet address
1st Host address
Last Host address
Broadcast
0
192.168.10.0
192.168.10.1
192.168.10.30
192.168.10.31
1
192.168.10.32
192.168.10.33
192.168.10.62
192.168.10.63
2
192.168.10.64
192.168.10.65
192.168.10.94
192.168.10.95
3
192.168.10.96
192.168.10.97
192.168.10.126
192.168.10.127
4
192.168.10.128
192.168.10.129
192.168.10.158
192.168.10.159
5
192.168.10.160
192.168.10.161
192.168.10.190
192.168.10.191
6
192.168.10.192
192.168.10.193
192.168.10.222
192.168.10.223
7
192.168.10.224
192.168.10.225
192.168.10.254
192.168.10.255
Problem 2:
IP address: 192.168.10.0 / 26 (given)
a. Custom Subnet Mask: _________________________________________
b. Bits Borrowed: _________________________________________
c. Number of subnets: _________________________________________
d. Magic number: _________________________________________
e. Number of valid hosts per subnet: _________________________________________
f. (Sub) network address of subnet 0: _________________________________________
g. First usable host address in subnet 0: _________________________________________
h. Last usable host address in subnet 0: _________________________________________
i. Broadcast address in subnet 0: _________________________________________
j. (Sub) Network address in subnet 1: _________________________________________
k. Last usable host address in subnet 2: _________________________________________
Subnet
Subnet address
1st Host address
Last Host address
Broadcast
0
1
2
3
Etc.
Problem 3:
IP address: 192.168.10.0 (given)
Subnet Mask: 255.255.255.240
a. Slash prefix: _________________________________________
b. Bits Borrowed: _________________________________________
c. Number of possible subnets: _________________________________________
d. Magic number: _________________________________________
e. Number of usable hosts per subnet: _________________________________________
f. (Sub) network address of subnet 0: _________________________________________
g. First usable host address in subnet 0: _________________________________________
h. Last usable host address in subnet 0: _________________________________________
i. Broadcast address in subnet 0: _________________________________________
j. (Sub) Network address in subnet 1: _________________________________________
k. Last usable host address in subnet 2: _________________________________________
Subnet
Subnet address
1st Host address
Last Host address
Broadcast
0
1
2
3
Etc.
Problem 4:
IP address: 192.168.10.0 (given)
Minimum number of subnets needed: 31
a. Slash prefix: _________________________________________
b. Subnet Mask: _________________________________________
c. Bits Borrowed: _________________________________________
d. Number of possible subnets: _________________________________________
e. Magic number: _________________________________________
f. Number of valid hosts per subnet: _________________________________________
g. (Sub) network address of subnet 0: _________________________________________
h. First usable host address in subnet 0: _________________________________________
i. Last usable host address in subnet 0: _________________________________________
j. Broadcast address in subnet 0: _________________________________________
k. (Sub) Network address in subnet 1: _________________________________________
l. Last usable host address in subnet 2: _________________________________________
Subnet
Subnet address
1st Host address
Last Host address
Broadcast
0
1
2
3
Etc.
Problem 5:
IP address: 192.10.10.0 (given) (Note that this address is slightly different than above)
Minimum number of hosts needed per subnet: 16
(Remember that the goal is to find a solution that will waste as few host addresses as possible but still satisfy the requirements.)
a. Slash prefix: _________________________________________
b. Subnet Mask: _________________________________________
c. Bits Borrowed: _________________________________________
d. Number of possible subnets: _________________________________________
e. Magic number: _________________________________________
f. Number of valid hosts per subnet: _________________________________________
g. (Sub) network address of subnet 0: _________________________________________
h. First usable host address in subnet 0: _________________________________________
i. Last usable host address in subnet 0: _________________________________________
j. Broadcast address in subnet 0: _________________________________________
k. (Sub) Network address in subnet 1: _________________________________________
l. Last usable host address in subnet 2: _________________________________________
Subnet
Subnet address
1st Host address
Last Host address
Broadcast
0
1
2
3
Etc.
Answer the following questions. Try to answer them without using tables to guide you:
1. How many usable hosts per sub-network will you have using a /20 address? ______
2. Given a Class B address, what is the magic number if you need to subnet using a /23 prefix? ______________________
3. In a Class B address, how many sub-networks can you have with a /18 prefix? _______________
4. How many total addresses per network can you have with a subnet mask of 255.255.224.0? (Note that total addresses include network and broadcast
addresses.)___________
