A network adapter cannot correctly communicate. After the netstat -rn command is executed, it is found that an invalid route is working on the network adapter:
0.0.0.0 0.0.0.0 0.0.0.0 U 0 0 0 bond0
After the route -delete command is executed to delete the route, bond0 is configured again after a period of time.
1. Open and check route configuration file cat /etc/sysconfig/network/routes. The route is not found.
10.0.40.103 10.80.152.254 255.255.255.255 bond1
default 10.80.152.1 - - S
2. Check bond0 file cat /etc/sysconfig/network/ifcfg-bond0. It is found that all the configurations except the IP address are the same as those of the bond1 file. It is suspected that the fault is caused by the IP address.
3. Run the crontab –l command. No scheduled tasks related to the route are found.
4. Check the cat /etc/profile file. It is found that the route add 0.0.0.0 mask 0.0.0.0.0.0.0.0 command is in the last line of the file. It is determined that this command causes that this file is read upon each login after the route is deleted and the command configured in the file is executed. As a result, the route is automatically generated again.
After this command is deleted, the fault is rectified.
1. It is suspected that this route is written in the /etc/sysconfig/network/routes file.
2. The route is configured in the bond0 file and the network adapter configuration file.
3. Check whether scheduled tasks exist in cron.
4. Check user environments ./bashrc and /etc/profile.
The /etc/profile file is important. Modify it only when necessary.