10 network protocol decryption faults

For networks, it is common to have some faults. Here we will introduce network protocol faults. This time we have summarized 10 network protocol faults. We hope these typical examples can help you solve these problems.

Network Protocol fault 1. The computer cannot access the external network

If the computer cannot access the external network normally, first check whether the network cable is correct. If the network cable works properly, it indicates that it can be connected to other computers in the network, and the network connection is normal. therefore, the cause of the failure may be that the IP address information is not complete, or the proxy server of the application is not correctly set. in this case, check whether the default gateway, DNS server, and subnet mask of the faulty computer are correctly set. in addition, check the Web browser connection settings of other computers and set the faulty computer to the same.

Network Protocol fault 2. IP address information is correct and cannot be accessed

If the default gateway, DNS server address, and IP address settings of the computer do not appear to be correct, but the computer cannot access the Internet normally, you can ping other computers in the network, default gateways, IP addresses and DNS of external Web sites.

If you cannot ping other computers in the network, it indicates that there is a problem with the IP address settings, or the TCP/IP protocol is not correctly installed, try to uninstall the TCP/IP protocol and restart the computer, add and install the TCP/IP protocol, and set the IP address correctly.

If you ping different default gateways, it indicates that the default gateway settings in the IP address information are incorrect. Check the settings carefully.

If the IP address of an external Web site cannot be pinged (you must first test the IP address on a connected computer to make sure that the IP address can be pinged), the default gateway settings in the IP address information are incorrect, or you have not installed the agent server software, or you have made restrictions on the proxy server or Broadband Router. You are not allowed to access the network using this IP address or MAC address.

If the DNS name of the Web site cannot be pinged, it indicates that the DNS server settings in the IP address information are incorrect. Check the settings carefully and configure the secondary DNS server.

If all the above ping tests are successful, you still cannot access the Web site. view the LAN Settings of Internet Explorer. enable "tool" à "Internet option" à "connection" à "LAN Settings" in turn, and deselect the "Automatic Detection Settings" check box ,. if you use a Broadband Router, or gateway proxy servers such as ICS and SyGate share Internet connections, deselect the "set proxy server for LAN" check box. if you use Wingate as the proxy server, select this check box and enter the IP address and port number of the proxy server. install system patches and virus firewalls.

Figure cancel LAN "Automatic Detection Settings"

Network Protocol fault 3. Ping DNS but cannot access the Internet

If you have correctly configured the IP address and proxy server address, and can ping the DNS server, you can also see other computers in "Network neighbors", but cannot ping the server or access the internet. the above problems indicate that there is no problem with the network connection. Check the settings of Internet Explorer. if the DNS and the computer are in the same subnet and are in the same IP address segment, you should specify the correct default gateway for the computer to route its Internet access requests to the external network.

Network Protocol failure 4. Ping other computers in the network but cannot ping the Gateway

Since you can ping other computers in the network, it indicates that there is no problem with the physical connection of the network and the network settings of the Local Machine. However, if you cannot Ping the gateway, there may be the following reasons for the inability to access the Internet:

(1) The default gateway settings are incorrect. Check whether the computer's default gateway settings are correct. If a Gateway error occurs, the computer cannot access the Internet.

(2) the proxy server restricts the IP address. The proxy server can set the IP address access list, and the rejected IP address will not be able to access the Internet.

(3) the computer is infected with the worm. When the computer is infected with the worm, access to the Internet is also directly affected. Update the Windows system patch in time and upgrade the Norton virus library.

Network Protocol failure 5. Unable to ping the Gateway

This problem may be caused by incorrect computer gateway or subnet mask settings. in a VLAN-based network, each VLAN has different IP address segments, subnet masks, and default gateways. therefore, when the default gateway is set incorrectly, it cannot be routed to other networks, resulting in network communication failure. the subnet mask is used to distinguish between the network number and the IP address number. If the default gateway is set incorrectly, communication between networks may fail. Check the settings of the default gateway and subnet mask carefully.

Network Protocol failure 6. Unable to ping computers in other network segments

If the computer can ping the computer in the current CIDR block but cannot ping the computer in other CIDR blocks, the reason may be that there is a problem with the subnet mask settings. the subnet mask is used to distinguish between network numbers and host numbers. Only computers with the same network number can be considered as the same network segment to implement communication between them.

Network Protocol fault 7. Slow startup after Nic is installed

After the NIC is installed, the system startup speed is much slower, which is normal. in addition to network connections, the computer automatically detects DHCP servers in the network. to accelerate the system startup speed, you should specify a fixed IP address for the computer, instead of dynamically assigning an IP address each time you start the system.

Network Protocol fault 8. IP address conflict

In a TCP/IP network, an IP address represents the identity of a computer and is used to identify a computer. therefore, the IP address must be unique in the same network. when two or more computers use the same IP address, an IP address conflict occurs. Other computers cannot determine which computer to send data to, resulting in network connection interruption. since ICS, proxy servers, or broadband routers are used for Internet Connection Sharing, you can directly use their automatic IP Address Allocation Function to allow all computers to automatically obtain IP addresses, this avoids IP address conflicts caused by manual IP Address Settings. for a client in the network, you only need to set the IP address and default gateway to "automatically get address", and the DNS server is usually set to the IP address of the DNS server of the ISP.

Network Protocol fault 9. IP address modification prohibited

You only need to bind the IP address of each computer to the MAC address of the NIC address. for example, to bind the IP address "192.168.1.100" with the MAC address "00-10-5C-B9-30-A8", click "start"-> "run", and enter the following command:

Arp-s 192.168.1.100 00-10-5C-B9-30-A8

To unbind an IP address from a MAC address, run the following command:

Arp-d 192.168.1.100

In Windows 2000, you can also use group policies to restrict users from modifying IP addresses and enable DHCP to dynamically allocate IP addresses.

Network Protocol failure 10. Computers in the LAN can access each other but cannot ping each other

The cause of mutual access between network peers, but the ping fails at the DOS prompt, it may be because the other party or a device in the network has disabled ICMP traffic (for example, filtering the ICMP port in the access control list of the switch) and Disabling ICMP response, which does not affect resource sharing.

Another possible cause is the network protocol. if all computers use the NetBIOS protocol, that is, the network neighbor function in the LAN is implemented through the NetBIOS protocol instead of the TCP/IP protocol, so ICMP is not supported, the ICMP protocol requires the support of the TCP/IP protocol. to enable the ping command between computers, you must install the TCP/IP protocol for the computers on the network.