Rick Troth wrote:
/etc/hosts can speed up some kinds of access (eg: NFS and YP).
But there is the obvious problem of [re]deploying a fully-populated
/etc/hosts file to every system in a changing network. I like
to have a standard "hosts.txt" (same format as /etc/hosts) on a
common web server or file server for reference, which would ease
the deployment problem, but I AVOID using it unless there is
some problem that might call for it.
The internet itself was driven by a massive /etc/hosts file
until DNS was invented (now more than fifteen years ago, I guess).
Deployment of that names file was a pain. It did not scale.
But there are occasions when one or two "hint names" are useful,
like the address of the local machine.
Now when I look at it, it would seem to be requried. After all, I'm
naming this node on the network.
Right.
But naming this node in /etc/hosts only serves this node.
That file is not consulted when this host tries to identify itself
(eg: via DHCP if a specific host NAME is requested). But it IS
consulted when applications (eg: Oracle?) refer to this host
by its reachable address (and not via the "loop back" addr).
But, I also thought that when I created the Host Name, and Name Server
Configuration, during the install, a default entry in the /etc/hosts
file would have been setup, if this was such an important entry.
This is an installation program feecher (or failure).
There is no stopping an app from using /etc/hosts as an API.
Sure, better to go thru the standard functions (now all in GLIBC).
But even there, why bounce off a DNS server for your own name?
It's a sysadmin call: Your network, your rules.
This is how RH configures the name server:
[EMAIL PROTECTED] ~]$ grep hosts: /etc/nsswitch.conf
#hosts: db files nisplus nis dns
hosts: files dns
[EMAIL PROTECTED] ~]$
The result is the hosts files is consulted before DNS and so is quicker.
However, glibc includes the Name Server Caching Daemon, nscd, and that
should make the difference pretty insignificant.
How often is Oracle fetching this info anyway? Is there a reason it
needs to do so more than once?
There's also the option of running a local DNS too.
--
Cheers
John
-- spambait
[EMAIL PROTECTED] [EMAIL PROTECTED]
Tourist pics http://portgeographe.environmentaldisasters.cds.merseine.nu/
do not reply off-list
----------------------------------------------------------------------
For LINUX-390 subscribe / signoff / archive access instructions,
send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit
http://www.marist.edu/htbin/wlvindex?LINUX-390
