I am running Ubuntu (12.04) on Virtual Box and want my machine to be able to lookup its own hostname, the same way other VMs will do in this network (I am trying to build virtual cluster). There is no DNS server, IP are assigned by VirtualBox, and I just map them in /etc/hosts.
The machine name is node1 and I have /etc/hosts like that:
user@node1-VirtualBox:~$ cat /etc/hosts 127.0.0.1 localhost 192.168.56.103 node1-VirtualBox.cs.ucl.ac.uk node1-VirtualBox #10.0.2.15 node1-VirtualBox # The following lines are desirable for IPv6 capable hosts ::1 ip6-localhost ip6-loopback fe00::0 ip6-localnet ff00::0 ip6-mcastprefix ff02::1 ip6-allnodes ff02::2 ip6-allrouters
So I would assume that
- Fully qualified hostname would be node1-VirtualBox.cs.ucl.ac.uk
- node1 and node1-VirtualBox.cs.ucl.ac.uk would resolve to 192.168.56.103 (and vice versa)
From hostname I am getting this:
$hostname -> node1-VirtualBox (OK) $hostname --fqdn -> node1-VirtualBox.cs.ucl.ac.uk (OK) $hostname --A -> node1.local node1.cs.ucl.ac.uk (OK i guess)
hostname looks promising, but when I try to get IP addresses using host, it doesn't work...
user@node1-VirtualBox:~$ host -v -t A node1-VirtualBox Trying "node1-VirtualBox.cs.ucl.ac.uk" Trying "node1-VirtualBox" Host node1-VirtualBox not found: 3(NXDOMAIN) Received 110 bytes from 127.0.0.1#53 in 1 ms user@node1-VirtualBox:~$ host -v -t A 192.168.56.103 Trying "126.96.36.199.in-addr.arpa" Host 188.8.131.52.in-addr.arpa. not found: 3(NXDOMAIN) Received 108 bytes from 127.0.0.1#53 in 2 ms
Any idea why this isn't working? From what I read and see in config, if DNS is done on localhost, it should just check /etc/hosts... and everything is there, right? And SSH is working, so clearly this file is correct?
Below my configuration:
# /etc/nsswitch.conf # # Example configuration of GNU Name Service Switch functionality. # If you have the `glibc-doc-reference' and `info' packages installed, try: # `info libc "Name Service Switch"' for information about this file. passwd: compat group: compat shadow: compat hosts: files mdns4_minimal [NOTFOUND=return] dns mdns4 networks: files protocols: db files services: db files ethers: db files rpc: db files netgroup: nis
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 OVERWRITTEN nameserver 127.0.0.1 search cs.ucl.ac.uk
ifconfig: eth0 Link encap:Ethernet HWaddr 08:00:27:da:a1:bc inet addr:10.0.2.15 Bcast:10.0.2.255 Mask:255.255.255.0 inet6 addr: fe80::a00:27ff:feda:a1bc/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:169 errors:0 dropped:0 overruns:0 frame:0 TX packets:176 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:123968 (123.9 KB) TX bytes:21551 (21.5 KB) eth1 Link encap:Ethernet HWaddr 08:00:27:99:65:51 inet addr:192.168.56.103 Bcast:192.168.255.255 Mask:255.255.0.0 inet6 addr: fe80::a00:27ff:fe99:6551/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:268 errors:0 dropped:0 overruns:0 frame:0 TX packets:252 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:78333 (78.3 KB) TX bytes:71866 (71.8 KB) lo Link encap:Local Loopback inet addr:127.0.0.1 Mask:255.0.0.0 inet6 addr: ::1/128 Scope:Host UP LOOPBACK RUNNING MTU:65536 Metric:1 RX packets:12527 errors:0 dropped:0 overruns:0 frame:0 TX packets:12527 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:0 RX bytes:23857104 (23.8 MB) TX bytes:23857104 (23.8 MB)
Ok, it turns out the "host" command not resolving was a bit of red herring for my original problem - it couldn't work because it doesn't look into /etc/hosts, as explained in answers below.
The original issue was lack of canonical hostname i.e.
hostname --fqdn was returning localhost. To fix it i had to have this:
192.168.56.103 node1-VirtualBox.cs.ucl.ac.uk node1-VirtualBox as second line in my /etc/hosts.
However for making it actually work i had to restart my machines and reinstall Cloudera on my cluster.