I have 4 ubuntu machines connected in a LAN network by a single switch.Their IP address is from 192.168.10.10-192.168.10.13.But after I restarted one of them since disk problem,I find that this machine cannot access internet(others can access internet),but all the 4 machines can be accessed from each other.I use sudo ufw status ,it shows inactive.I use cat /etc/hosts , it shows:127.0.0.1       localhost192.168.10.12   mongodb# The following lines are desirable for IPv6 capable hosts::1     ip6-localhost ip6-loopbackfe00::0 ip6-localnetff00::0 ip6-mcastprefixff02::1 ip6-allnodesff02::2 ip6-allroutersThe others have the same config(of cource the LAN ip is different).So , I really don't know what happened.I tried to use command sudo ifconfig eth0 restart,it reports:Host name lookup failuremongodb@mongodb:/var$ ifconfig eth0eth0      Link encap:Ethernet  HWaddr d4:ae:52:c9:61:5f            inet addr:192.168.10.12  Bcast:192.168.10.255  Mask:255.255.255.0          inet6 addr: fe80::d6ae:52ff:fec9:615f/64 Scope:Link          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1          RX packets:16199 errors:0 dropped:91 overruns:0 frame:0          TX packets:14260 errors:0 dropped:0 overruns:0 carrier:0          collisions:0 txqueuelen:1000           RX bytes:2198421 (2.1 MB)  TX bytes:2664354 (2.6 MB)mongodb@mongodb:/var$ cat /etc/resolv.conf # Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)#     DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTENnameserver 192.168.10.1mongodb@mongodb:/var$ route -nKernel IP routing tableDestination     Gateway         Genmask         Flags Metric Ref    Use Iface0.0.0.0         192.168.10.1    0.0.0.0         UG    100    0        0 eth0192.168.10.0    0.0.0.0         255.255.255.0   U     0      0        0 eth0
One ubuntu machine in LAN cannot access internet
linux;ubuntu;hostname;hosts