hostname and DNS
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From: Wayne on 11 Aug 2010 19:32 On 8/11/2010 2:40 PM, Lao Ming wrote: > What makes /bin/hostname use an old DNS name instead of the name that / > usr/bin/dig displays? I have a script which uses $( hostname -s ) to > obtain the hostname. Even though the DNS update was done at least a > month ago, /bin/hostname continues to provide the name that I don't > want. I also have the hostname defined properly in /etc/hosts. > Should I mention it to the DNS admin or is there some way to force > getting the correct name? (This of OT here, try a networking group.) /bin/hostname returns the kernel's idea of your hostname; dig, host, nslookup, getent, and no doubt other utilities I can't remember, all do a lookup; usually returning the DNS system's idea of the name associated with some IP address (usually the first address bound to the first detected NIC). The kernel's hostname (also known as a nodename) is not dependent on DNS or any IP address. The host name is usually set at boot time from some RC script. On Fedora Linux for example, this is set in the file /etc/sysconfig/network, which is read by several init scripts. A similar problem can occur due to caching of names. Then when you change the name the cache still reports the old value. /bin/hostname doesn't do any lookup so this isn't the problem in your case, but if you've recently updated your DNS data (or /etc/hosts file or other host DB), make sure to flush the name service cache. Finally, some services ignore both the DNS and kernel's idea of the hostname and use a setting in their configuration files to determine the server's name. Apache, Postfix (MTA), and many others may set the server name. Usually you need to run a shell script (see? I worked that in) to find all occurrences of the old hostname in all files under /etc. -- Wayne
From: Bill Marcum on 12 Aug 2010 22:41
On 2010-08-11, Lao Ming <laomingliu(a)gmail.com> wrote: > What makes /bin/hostname use an old DNS name instead of the name that / > usr/bin/dig displays? I have a script which uses $( hostname -s ) to > obtain the hostname. Even though the DNS update was done at least a > month ago, /bin/hostname continues to provide the name that I don't > want. I also have the hostname defined properly in /etc/hosts. > Should I mention it to the DNS admin or is there some way to force > getting the correct name? Your /etc/hosts file contains the correct hostname for a particular IP address. Is that the same IP address shown by '/bin/hostname -i' ? Another thing you might check is the DHCP configuration. If your machine is a DHCP client, the server might be feeding it the old hostname. -- Vacuums are nothings. We only mention them to let them know we know they're there. |