The last big question - applied questions, has the following test points. You don't need to understand the principles and can calculate. It is not difficult to get 10 points from 15 points. It is recommended to take a look. >_<
Table of contents
1. Determine the IP address type
2. Find the subnet mask through the IP address
3. Find the network address and broadcast address
4. Find the host number and available IP
6. Group the port into a VLAN command
7. Write routing configuration commands
1. Determine the IP address type
Simply put, the IP address range of Class A network is 1.0.0.1 - 126.255.255.254, the IP address range of Class B network is 128.1.0.1 - 191.255.255.254, and the IP address range of Class C network is 192.0 .1.1 - 223.255.255.254.
Note: 127.0.0.0 to 127.255.255.255 are reserved addresses, used for loop testing, 0.0.0.0 to 0.255.255.255 are also reserved addresses, used to represent all IP addresses, the highest bit of the network address of a class A address must be 0, B The highest digit of the network address for a class address must be 10, and the highest digit of the network address for a Class C address must be 110.
2. Find the subnet mask through the IP address
For example, the question gives an IP address of 10.10.10.5/30. Let us find its dotted decimal mask.
What does /30 here mean?
The IP address converted into binary is 32 bits. /30 means that the first 30 bits are network bits and the last two bits are host bits. To find the subnet mask, you need to change all the network bits to 1 and the host bits to 0. , that is, the first 30 bits are 1 and the last two bits are 0.
The first step is to convert the IP address into binary, 00001010.00001010.00001010.00000101,
The second step, subnet mask = 11111111.11111111.11111111.11111100,
Finally, change the mask back to decimal, 255.255.255.252.
Eight ones is 255. In fact, after you become proficient, you don't need to convert everything into binary. Anyway, the previous bits will become 1 in the end. You only need to observe the changed positions based on the numbers after /.
3. Find the network address and broadcast address
Here are two definitions:
① Network address: The network bits remain unchanged and the host bits are all 0;
② Broadcast address: The network bits remain unchanged and the host bits are all 1.
This means that when finding the network address or broadcast address, first convert the IP address into binary, then the network bit remains unchanged, and the host bit becomes 1 or 0 accordingly.
For example, the question gives an IP address of 10.10.10.5/30. What are the network address and broadcast address of the network where this IP address is located?
The first step is still to convert the IP address into binary, 00001010.00001010.00001010.00000101,
The second step is to perform conversion according to the definition of network address and broadcast address.
Network address = 00001010.00001010.00001010.00000100
Broadcast address = 00001010.00001010.00001010.00000111
The third step is to convert binary to decimal.
Network address = 10.10.10.4, broadcast address = 10.10.10.7.
During the exam, you should write out the calculation process as shown above to let the teacher know how you calculated it, and be as detailed as possible.
Sometimes the question will not directly give you information like /30, but will give you an IP address and a subnet mask, allowing you to calculate the corresponding network address and broadcast address. At this time, you can think about the subnet mask. The definition of the code, the subnet mask is obtained by changing all the network bits to 1 and the host bits to all 0. Now given the mask, we directly change the mask into binary and count the number of previous 1's. You will know how many network bits and how many host bits there are. After the number of bits is determined, you can easily calculate the result based on the known IP address and the definition of the network address and broadcast address.
4. Find the host number and available IP
Concept definition:
① Host number: Keep the host bits unchanged, change all network bits to 0, and then convert it to decimal;
② Available addresses: All addresses between the network address and the broadcast address.
Still using the above example, the IP address given in the question is 10.10.10.5/30. Find the host number and available IP.
Convert the IP address to binary, 00001010.00001010.00001010.00000101,
The host bit remains unchanged, the network bit is all 0, the host number = 00000000.00000000.00000000.00000001, which converted to decimal is 0.0.0.1.
We have already calculated the broadcast address and network address above. The range of intermediate addresses from 10.10.10.4 to 10.10.10.7 is: 10.10.10.5 - 10.10.10.6.
5. Selection of twisted pair
Twisted pair cables can be divided into straight-through cables and crossover cables. The question will ask which cable should be used to connect the two devices?
I won’t go into details about the principle. In a word, use crossover cables for the same type of equipment and straight-through cables for different equipment.
Commonly,use a crossover cable to connect the router to the PC, use a straight-through cable to connect the switch to the PC,use a crossover cable to connect the switch to the HUB, Crossover cables are used to connect routers and routers, and straight-through cables are used to connect routers and switches.
Especially remember the first two, we can also understand it this way:
Routers and PCs belong to DTE (data terminal equipment) and are the same type of equipment. Switches and HUBs belong to DCE (data communication equipment) and are the same type of equipment.
6. Group the port into a VLAN command
Among them, f0/6 is the port number. Replace it according to the question. You can memorize it directly and just replace the port number.
7. Write routing configuration commands
The score for router configuration commands is about 3 to 4 points. It is very difficult to get full marks. It is easy to get the commands wrong. The main reason is that I didn’t understand it myself. Sorry!