1. What is the ip address
In the network, all devices are assigned an address. This address is equivalent to a certain way of XX XX No. rooms. [No.] wherein the corresponding number is assigned to an entire subnetwork, the number corresponding to [the chamber] is assigned to the subnet of the computer, which is a network address. [No.] network number corresponding to the number called, the number corresponding to [the chamber] is called host number, the entire address called an IP address. Through this we can locate the IP address of the server.
2, IP address format
Because humans rely decimal, so the IP address here expressed in decimal way
Let the machine identification, or have converted to binary
(Decimal IP address) 14.145.184.184
(Binary IP address) 00,001,110.10010001. 10,111,000.10111000
This method represents IP mode, called the IPV4, each IP address is represented by a 4 * 8 = 32
In this case, there are a number of IP addresses it?
00000000 00000000 00000000 00000000 minimum address is 0.0.0.0
1,111,111,111,111,111 1,111,111,111,111,111 maximum address is 255.255.255.255
IPV4 way, can represent up to 255 * 255 * 255 * 255 = 4,228,250,625 = 4,000,000,000 ip address has now run out
3. Private IP
In order to solve the case of shortage of public IP addresses, the invention thus private IP (Private IP)
For example, a family (company) have several computers, each computer has a private IP, consisting of a local area network between them
These private IP, through certain techniques (NAT), share a public IP
In other words, a public IP, you can separate many have a lot of Private IP, IPV4 lack of such a problem is solved
In order to better manage the private IP divided into three types
CLASS A：10.0.0.0 ~ 10.255.255.255
CLASS B：172.16.0.0 ~ 172.31.255.255
CLASS C：192.168.0.0 ~ 192.168.255.255
4, IP address is how composed
Find the IP address, you can find the house number analogy by courier
Each building has a floor, for example 4 building, Building 5, etc.
Each building has a house number, such as Room 101, No. 102 and the like Room
IP address also has two partial address, namely the "network address (network number)" and "host address (host ID)."
Different categories (A, B, C) of the division "network number" and "host ID" is different, there is a table
As long as "network number net_id (purple)" IP address is the same, we'll call these IP addresses in the same network segment
Mutual access to each other, such as playing online games
When the host number are all 0, the first representing the whole building a house, also known as network address network ip
When whole host No. 1, representing the whole building and finally a house, also called broadcast address broadcast ip
5, the subnet mask is what? what's the effect?
Or make an analogy with building No. Well
In reality, we can say so, Building 1, Room 201 on the
IP address, the figures are linked together, 10101010.10101010.10101010.00000001
how do we know which part is the floor? Which part is the room number it? How to divide it?
The answer is the subnet mask by --Netmask
Mask means, it is to conceal a portion of the code, while exposing another portion of the code
Subnet mask, in order to conceal the "network number net_id", exposed the "host number host_id"
Expressed as a cover for 1
with 0 exposure
With this, for example, IP address notation: 10.10.10.1/24 10.10.10.1/25
24 illustrates the subnet mask covered the 24, also illustrates this IP "network number net_id" is 24, the segment accounted for 24
25 illustrates the subnet mask covered the 25, also illustrates this IP "network number net_id" is 25, the segment accounted for 25
Because 10.10.10.1/24 and 10.10.10.1/25 "network number" different, different segments
The network address (a first IP address), the subnet mask (binary) operation with the derived IP address (binary) and
The binary 10.10.10.1/24 10.10.10.1 is 10101010.10101010.10101010.00000001
10.10.10.1/24 subnet mask is 1,111,111,111,111,111 1,111,111,100,000,000
so the network address is in 10.10.10.1/24 10101010.10101010.10101010.00000000, i.e. 10.10.10.0
broadcast address 10.10.10.1/24 is 10101010.10101010.10101010.11111111 that 10.10.10.255
so this network segment can be allocated to a total of 254 IP addresses used by the host, from 10.10.10.1 ~ 10.10.10.254
The binary 10.10.10.1/25 10.10.10.1 is 10101010.10101010.10101010.00000001
10.10.10.1/25 subnet mask is 1,111,111,111,111,111 1,111,111,110,000,000
so the network address in the range 10101010.10101010.10101010.00000000 10.10.10.1/25, i.e. 10.10.10.0
10.10.10.1/25 a broadcast address 10101010.10101010.10101010.01111111, namely 10.10.10.127
(address change when the network broadcast address, subnet mask because the mask the 25, so only the last 27 becomes 1)
Therefore, this segment can be, can be assigned to hosts using a total of 126 addresses from 10.10.10.1 ~ 10.10.10.126
10.10.10.1/24 and 10.10.10.1/25
One is the subnet mask of the IP address 10.10.10.1 24
25 is a subnet mask for the IP address of 10.10.10.1
Two surfaces are the same IP address, subnet mask, but because different, resulting in different network segments
Like a building has 201 rooms, the second floor also has 201 rooms, two rooms but not in the same room
10.10.10.1/24 and 10.10.10.1/25 also two IP addresses
link: https: //www.zhihu.com/question/29723388/answer/66737890
Source: know almost