Dividen Subsidiary Detailed Drawn (Network Basic Exam Tit) 1, assuming the network address 200.200.200.0, the subnet mask is 255.255.255.0. Now there is 100 hosts in one subnet, and the other 4 subnets have 20 hosts. How to divide the subnet to meet the requirements. Please write a subnet mask, network address, the first host address, the last host address, and the broadcast address. (The subnet number can be all 0 and all 1). Please write the last answer directly.
Before you haven't doing questions, you must clarify the naming method of the IP address, the essence of the subnet, and the role of the subnet mask.
The format of the IP address is (32bit) = NET-ID HOST-ID
When the outside world wants to communicate with my computer, he first finds the same router as my Net-ID, and then find my host-id by the router.
IP address is generally divided into three categories: Class A: IP (32bit) = NET-ID (8bit) Host-ID (24bit)
The general form is: IP = X.
0. 0. 0
The latter 0 is the host number
Class B: IP (32BIT) = NET-ID (16bit) Host-ID (16bit)
General: IP = X. X. 0. 0 behind the main unit
C Class: IP (32BIT) = NET-ID (24bit) Host-ID (8bit)
General: IP = X. X. X.0 behind 0 is the host number
Understand the format of the IP address, then we can understand the essence of subnet division.
Subnet division is to solve the case where the network IP is not enough, it is actually that the number of the host number bits that are originally assigned to it in the A, B, or Class C are in the network number. This will alleviate the case where the network IP is not enough.
For example, we take a Class B IP to divide: there is 16 host-id bits in XX0.0. At this time, you can take a number of bits to make NET-ID according to specific needs (specifically need a few times). For Host-ID. (At this time, you may ask, take the number of host number bits, that can be even less than the number of hosts? It is true that the division subsidiary is to increase the number of networks with the number of horses. The fact is true, many enterprise units have not so many hosts, but he is a big network ID, the IP address is not enough, it is caused by this reason)
Ok, I know that the essence of the division is to divide the Host-ID to make Net-ID. How is the outside world contact with the host in the subnet?
In the case where there is no subnet mask, the host connection within the subnet must contact the total network router before the previously did not divide, and then look up all the hosts in the network, so efficiency is very low. Can you make each subnet communicate over your own route and outside? The mask is to solve this problem.
Each subnet should communicate alone in the outside world, you must let the outside world know that you are divided into the subnet, your specific network ID. However, the routing table does not have the specific information of the subnet, so the outside world will not contact you through your router. The mask is that the NET-ID corresponds to the local mark corresponding to the NET-ID, and then adds a mask in the routing table, so the external It is easy to know your specific network ID. This is the role of the mask.
Let's take an example. 200.200.200.0 is a C class address. Requires a subnet 100 host, another four subnet 20 host, we can first divide the network into two subnets. A subnet to 100 hosts, a four subnets give another 20 host. Class C addresses have 8bit host numbers, and the division subnet is to take several bits of the host number to make the network ID.
Specifically, you have a formula here: the number of horses of the subnet = 2 -2 (X is the number of bits of the host number)
Now the number of hosts is 100, and we take 2 X-2-2 slightly greater than 100. That is, x = 7.
In other words, the number of host number is 7 bits, and this subnet can connect 100 hosts. Originally, there were 8, the rest of the place was taken as the network number. (It is also really a compromise, this bit can identify the red part of the next two subnets (0 or 1)!)
NET ID 200.200.200.00000000
Netmask 255.255.255.00000000
Subnet 1:
NET ID 200.200.200.00000000
Netmask 255.255.255.10000000 (mask is to use 1 identity network ID, see blue part)
Subnet 2:
NET ID 200.200.200.10000000
Netmask 255.255.255.10000000
Next, four subnets are divided into any of the subnets above. Here is a subnet 2.
From the above formula, the number of hosts in the subnet = 2 -2 -2
The X-2 of the X-2 is slightly greater than 20, that is, X = 5.
That is, the number of host numbers is 5, just 7 digits, the remaining 2 when the network ID is left.
Subnet 2.1:
NET ID 200.200.200.10000000
Netmask 255.255.255.11100000
Subnet 2.2:
Net ID 200.200.200.10100000
Netmask 255.255.255.11100000
Subnet 2.3:
NET ID 200.200.200.11000000
Netmask 255.255.255.11100000
Subnet 2.4:
Net ID 200.200.200.11100000
Netmask 255.255.255.11100000
In this way, the subnet is completed.
Next, write the subnet mask, network address, the first host address, the last host address, the broadcast address, and the broadcast address are relatively simple.
Remember this:
The host number is 0 is the network address, the network address 1 is the first host address, the host number 1 is a broadcast address. Broadcast address -1 is the last host address.
Subnet One host number is all 0: Net ID 200.200.200.000000 After eight 0 is binary, it is a network address, then 1 is the host address; the broadcast address should pay attention, the red 0 is a network ID, the host number is the seven 0 behind, and the 7 0 is all 1 is his broadcast address.
Next, this is then pushed.
Subnet mask
website address
First host address
Last host address
Broadcast address
255.255.255.128
200.200.200.0
200.200.200.1
200.200.200.126
200.200.200.127
255.255.255.224
200.200.200.128
200.200.200.129
200.200.200.158
200.200.200.159
255.255.255.224
200.200.200.160
200.200.200.161
200.200.200.190
200.200.200.191
255.255.255.224
200.200.200.192
200.200.200.193
200.200.200.22200.200.200.223
255.255.255.224
200.200.200.224
200.200.200.225
200.200.200.254
200.200.200.255
