Why is the ip address unavailable?

The IP address is unavailable due to illegal or invalid IP, network configuration error, network connection failure, IP address conflict, firewall or network security settings, ISP restrictions and server failure. Detailed introduction: 1. Illegal or invalid IP, the entered IP address is invalid, the system will consider the IP to be unavailable; 2. Network configuration errors, wrong subnet masks, incorrect gateway settings, DNS configuration issues, etc. Cause; 3. Network connection failure, the IP address may be unavailable because there is a problem with the network connection itself; 4. IP address conflict, etc.

#With the widespread application of the network, the scale of the network continues to expand, and the corresponding IP address allocation is also increasing. The phenomenon of IP address conflicts is increasing day by day. To a certain extent affecting the normal operation of the network. Maintaining network stability and efficient operation and resolving IP address conflicts have become one of the important tasks in network management. What are the causes of IP conflicts? How to solve the problem of IP conflicts?

When we encounter When you get the "IP address unavailable" error, there may be some of the following reasons:

1. Illegal or invalid IP: In network communication, the IP address is the unique address used to identify the network device. If the entered IP address is invalid (such as incorrect format, out of range), the system will consider the IP to be unavailable.

2. Network configuration error: Another common reason for unavailable IP addresses is network configuration error. This can be caused by a wrong subnet mask, incorrect gateway settings, DNS configuration issues, etc.

3. Network connection failure: The IP address may be unavailable because there is a problem with the network connection itself. For example, network equipment (such as routers, switches) fails, network cables are damaged, network interruptions, etc.

4. IP address conflict: When multiple computers or devices try to use the same IP address, an IP address conflict occurs. This results in the IP address being unavailable because the network cannot identify which device should use that IP address.

5. Firewall or network security settings: Sometimes, firewall or network security settings may prohibit access from specific IP addresses. This may be for security reasons to prevent untrusted or malicious IP addresses from accessing the network.

6. ISP restrictions: Some Internet service providers (ISPs) may restrict or block specific IP addresses. This may be for security, traffic control, or other reasons.

7. Server failure: If you cannot access a specific IP address, it may be because the target server is faulty, undergoing maintenance, or temporarily closed.

1. Personal IP address conflict resolution

1. If the operating system of the computer you are using is: windows (windows7 or window10 will work).

Command signaling is required here:

ipconfig /release releases the IP address.

Then you need to obtain ipconfig /renew again.

Let’s take a look at how to solve them:

You can click "Start" → "Run" in the lower left corner, type: ipconfig /release, click "OK" to release the IP address.

The network will be disconnected at this time because the IP address has been released.

Click "Start" → "Run" again, type: ipconfig /renew, click "OK", and re-obtain the IP address to resolve the IP address conflict.

At this time, the network will be reconnected, but the IP address is different from the original one and is reassigned to an available IP address to connect to the network.

2. Solution to LAN IP address conflict

Option 1. Check one by one

This is the most original method, that is, when an IP address conflict occurs , in the LAN, check next to each computer, find the computer that conflicts with it, and then modify the IP address. However, this is more time-consuming and is not suitable for use in large LANs. It is only suitable for use in small network environments.

Option 2. MAC address binding

1. Check the MAC of the local computer and bind it: by running Winipcfg/all in the local computer system, You can detect the MAC address of the network card.

So how to bind the ip address and mac physical address?

First enter cmd to enter the command configuration, and then enter the command ipconfig/all to check the local ip and mac address.

Enter the string command "arp -s 10.168.1.1 34-F3-9A-2B-9E-13" to bind.

Then enter the command arp -a to check whether the binding is successful.

Obviously, the default gateway address 10.168.1.143 is successfully bound to 36-F3-9A-2B-9E-13. Once the MAC address is up, if other workstations grab the 10.168.1.143 address when surfing the Internet in the future, they will be unable to access the Internet. In this way, the operational stability of the entire local area network can be guaranteed.

Option 3: Port isolation

For the IP address conflicts encountered, you can also use the switch ports to isolate different departments to solve the problem. This is because Switches can be used to implement different management for different areas. The divided network segments do not interfere with each other and can be Solve the problem of IP address conflict and data problem to a certain extent.

For a network with only one VLAN, port isolation is still necessary.

Let’s take a look at an example:

For example

Generally, a branch can only have one vlan. Under the same VLAN, data shielding between business department A and business department B in the branch can be achieved without hindering data exchange between all departments and the server in the headquarters computer room. However, in order to ensure that orders are accurately issued to the production department, the departments Department A and Department B can communicate with the production department.

Network topology diagram

1. Set the IP addresses of the three departments: IP address of business department A:

92.168.10.2 255.255.255.0

Business Department B’s IP address:

192.168.10.3 255.255.255.0

Production Department’s IP address:

192.168.10.4 255.255 .255.0

2. Layer 3 switch configuration (taking Huawei switch as an example

system configuration

[Huawei]sysname S5700

[S5700]vlan 10

[S5700-vlan10]quit

[S5700]int vlanif 10

[S5700-Vlanif10]ip address 192.168.10.1/24 //Configure gateway

[S5700-Vlanif10]quit

[S5700]int g0/0/1 //Enter port g0/0/1

[S5700-GigabitEthernet0/0/1]port link- type access //Configure port mode

[S5700-GigabitEthernet0/0/1]port default vlan 10 //Add vlan10

[S5700-GigabitEthernet0/0/1]port-isolate enable //Join port isolation group 1, and the isolation mode is Layer 2 isolation and Layer 3 interworking.

[S5700-GigabitEthernet0/0/1]quit

[S5700]int g0/0/2 //Enter port g0/0/2

[S5700-GigabitEthernet0 /0/2]port link-type access

[S5700-GigabitEthernet0/0/2]port default vlan 10

[S5700-GigabitEthernet0/0/2]port-isolate enable //By default, it is added to port isolation group 1, and the isolation mode is Layer 2 isolation and Layer 3 interworking.

[S5700-GigabitEthernet0/0/2]quit

[S5700]int g0/0/3 //Enter port g0/0/3

[S5700-GigabitEthernet0 /0/3]port link-type access

[S5700-GigabitEthernet0/0/3]port default vlan 10

[S5700-GigabitEthernet0/0/1]quit

3. Test results

Business Department A test results, Business Department B are similar

Production Department test results

Option 4: Divide vlan

Although switches can be used to isolate network segments, thus avoiding IP address conflicts to a certain extent, it still cannot prevent the occurrence of IP address conflicts. IP address conflicts caused by user configuration errors in the network segment under the same port. A better solution is to use switches to divide VLANs, and then use MAC address binding to handle it comprehensively.

We mentioned the method of dividing vlan before. If you need to know more, you can check:

has detailed explanations.

Summary:

If you need to avoid LAN IP address conflicts, it is best to bind the IP address to the computer MAC address and arrange the IP addresses uniformly. Computer users cannot change the IP address by themselves. If they change the IP address, they will not be able to access the Internet. New users need to obtain the assigned IP address from the administrator, so that most IP conflict problems can be avoided.

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