Two subnetted questions, subnetted network test questions solved?

1.A company obtains an address block from an operator and tries to divide it into 4 address blocks, and it is known that the number of host bits in each address block is 245,112,15,8, and tries to write out the address block.

A: According to the number of digits, it is divided as follows:

245 hosts are required, and 254 addresses are actually available.

112 hosts are required, and 126 addresses are actually available.

15 hosts are required, and 30 addresses are actually available.

8 hosts are required, and 14 addresses are actually available.

Address Try dividing it into four subnets and write out their network addresses, subnet masks, and assignable IPs for each subnet

Divided into 4 subnets, it is obtained:

I hope it helps.

256 addresses, 254 available.

128 addresses, 126 available.

32 addresses, 30 available.

16 addresses, 14 available.

The second question is, didn't you say how big the block was given and how big the block should be? Can't solve

1. The subnet mask is 19 bits, that is, the network bit is 19 bits, and the host bit is 32 19 13 bits. The maximum number of hosts that can be accommodated in each subnet is 13 bits, and the number of hosts 2 to the power of 13 is 2 8190.

2. The default of class B address is a 16-bit subnet mask, and now it becomes 19 bits, which is to borrow 3 bits of the host to divide the subnet, so the number of bits of the subnet is 3 bits, and it is divided into 8 subnets to the 3rd power of 2.

3. The subnet mask is 22 bits, so the host bit is 32 22 10 bits. The host is 10 bits, and the number of hosts that can be accommodated is 2 to the 10th power of 2 1022.

4. The default of the C address is a 24-bit subnet mask, and now the socks take 28 bits, that is, the host bit has 32 28 4 bits, so the host bit is 4 bits, and the number of hosts is 2 to the 4th power of 2 2 14.

5. It is the broadcast address. From the subnet mask, we can know that the subnet mask is 27 bits, so the increment of the subnet is 32, that is, the range of each subnet is: 0 31, 32 63, so the subnet is located, and this subnet takes all the host bits 1 to be the broadcast address

6. It is the host address. The subnet you are in by 5 can be known to be located, so is a usable host address.

7. Divide 10 subnets, you must divide 16 subnets, because 2 of the 3rd power 8 is not enough, or it can only be 2 of the 4th beam fiber square 16. To divide 16, you need to borrow 4 bits to divide the host, so the subnet mask has changed from the original 24 bits to the current 28 bits. So the subnet mask is.

This is the 28-bit subnet mask (the number of 1s is 28).

1. The number of people who like the most (small train) is the largest. The least number of people who like (blocks) the most.

2. I like building block toys, and I like this kind of play with six people the most.

Idea: Start with the largest number of hosts, start with the mask, start from the non-full 0 and all 1 in the mask binary, or start the analysis from the end of all 1, all 1 is the network bit, and all 0 is the host bit.

The mask here is 16, which is 11111111 11111111. 00000000.00000000 to borrow the host bit from 0 after all 1 to act as a network bit.

Divide the mask into 4 segments, each with 8 digits. Looking at this section of "00000000", when each host bit 0 is borrowed from left to right to act as network bit 1, it indicates that the number of subnets is 2 n. For example, if 10000000 is borrowed from 1 bit, the number of subnets is 2 1=2 subnets; 11000000, 2 bits are borrowed, which indicates that the number of subnets is 2 2=4 subnets.

Let's look at the number of hosts, mask 11111111 11111111. 00000000.00000000, the simple and crude method is to directly count a few 0s behind there are 2 n hosts.

Now to break it down, there are up to 600 hosts in 8. 2 n 600, n is 10, and there are 10 zeros after the description, that is, the mask is 11111111 11111111.

11111100. 00000000。Looking at the 11111100 part, if you borrow 6 bits, you will have 2 6 = 64 subnets, and 256 host addresses are divided into 64 networks, so each network has 256 64 = 4 host addresses.

So the network range of 8 is, (where is the network number, is the broadcast, and the valid address needs to be removed from these two).

Now it's the other way around. , 0-3 is exactly 4 addresses, and then counting the next 256 addresses is 4*256=1024 host addresses, which meets the needs of 600. 10 zeros behind the mask, 2 10 = 1024. So no problem.

Next3 requires 500 hosts, which need to be divided from the remaining addresses.

2 n 500, n = 9, to meet the needs of 3, so the host bit occupies 9 0s, that is, from 11111111 11111111. 11111100.00000000 borrow one.

It becomes 11111111 11111111. 11111110. 00000000。Same as 8.

So the network range of 3 is.

The rest is the same as the analysis. The result is:

Number twenty-six? Is it possible for a maker at home......It won't be too late, it won't be......I don't want to walk all the steps, you say no, no, I want to dress up.

When am I going to come back, I don't know when I'm coming back, I don't know when I'm coming back, I don't know when I'm coming back, I don't know when I'm coming back, I'm not going to go, I don't know when I'm coming back, I'm not going to go, I'm not going to be when I'm back, I'm not going to be when I'm coming back, I'm not going to be going, I'm not going to be going when I'm back, I don't know when I came back, I don't know when I came back, I don't know when I came back, I don't know when I came back, I don't know when I won't go, I don't know when.

What is a subnet?

A part of the network is a subordinate system of the master network, a small network that operates in a larger network, and it allows multiple types of devices to be connected to the network.

c. A division of a larger network to make it a smaller shard D, a smaller network, which maintains a database of all MAC addresses on that network.

Subnetting is for.

Simplified management and easy geographic reach.

In order to improve the utilization rate of IP addresses, the addresses of the three categories of ABC are divided into finer network segments by using masks, so as to save the waste of IP addresses as much as possible!

Subnet division is based on taking away the host bit, and the part taken away is used as the subnet bit, and the subnet number and the broadcast address of each subnet occupy 2 addresses, so the subnet subnet will be divided and the host will be fewer.

Instead of increasing the number of available IP addresses, subnetting reduces the number of available IP addresses.

The 16-bit mask given in the question can generate more than 65500 IPs, and the three networking requirements add up to almost 4W, always saying that the address is enough, and if it is strictly divided, there can be some addresses left after the division.

Estimate according to the needs of the topic:

a.200 subnets are required, 128 hosts 8 bits are required for subnets, and 7 bits are required for host bits (the total number of IPs is about 25600).

b.400 subnets are required 16 hosts 9 bits are required for subnets and 4 bits for hosts (the total number of IPs is about 6400).

c.2000 subnets are required, 4 hosts 11 bits are required for subnets, and 3 bits are required for host bits (the total number of IPs is about 8000).

Therefore, according to the analysis of requirements, it is found that A molecular network only needs 15 bits, B needs 13 bits, and C needs 14 bits.

Then, we can divide it into 2 large subnets first

Available IP range for subnet:

Available IP Ranges:

Let's go to 1 againSubnet to a with just 200 subnets Subnet 128 hosts:

The original 17-bit mask + the current 8-bit mask The subnet mask required by A is as follows:

.There are a total of 256 subnets, and the rest of the B, C, and demand are the same.

2^x>=6,x=3

2^y-2>=35,y=6

Because 3 (subnet bits) + 6 (host bits) > 8 bits. So a Class C address alone is not enough to allocate. Either give 1 more Class C address or a Class B address.

Supplementary question: The host number is incorrect.

For example, if the first address is taken as 0, it is equivalent to the IP address with all binary host bits 0 referring to the network itself);

If you take 31, it means that the address with all the binary host bits 1 is the broadcast address of the network). Remember, all host binary all 0s and all 1s won't work!

Take the first 3 bits of the fourth byte of this class C address as the subnet division, and get that the 3rd power of 2 is equal to 8 subnets.

The remaining 5 bits are used as host addresses, giving 2 to the power of 5 minus 2 (excluding network addresses and broadcast addresses) equals 30 host addresses.