Unix Tip: Cleaning up DNS

By Sandra Henry-Stocker

I recently had an occasion to help a friend update her DNS configuration on a system responsible for a small test domain. Since she seldom touches the zone files on the server, never mind the main configuration file, I suggested that we pay attention to the messages that the process writes to the messages file to highlight any configuration problems that existed in the long neglected named.conf file.

While we didn't run into many problems and the DNS server was working, we noted a number of minor configuration problems -- some resulting in errors and others generating warnings -- which we systematically identified and then resolved.

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Windows Tip: Building a supportable enterprise, part 2

By Mitch Tulloch, MTIT Enterprises

IT pros are by nature people who like to "mess around" with things. They're basically creative people who are easily bored, who enjoy challenges, and who usually prefer to tweak than to leave well enough alone. At least, that's me in a nutshell -- maybe I'm just a frustrated entrepreneur. Unfortunately, tweaking can easily get you in trouble, even when the best of intentions are involved.

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Windows Tip: Building a Supportable Enterprise - Part 1

By Mitch Tulloch, MTIT Enterprises

There are lots of different ways you can approach building an enterprise Windows network. Some of these ways are supportable though while others aren't. A supportable network is one you can administer easily and where you can get help from Microsoft Customer Support Services (which was formerly called and still frequently referred to as Product Support Services or PSS). An unsupportable network however is one that has become difficult to administer, and if it gets really bad then CSS may tell you that your only option is to flatten and rebuild everything from scratch. Clearly it's better to keep your Windows-based network supportable than let it become unsupportable. How do you do that?

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Unix Tip: Clearing the screen

By Sandra Henry-Stocker, ITworld.com

Every now and then I come across a system which, when I issue a request to clear the screen (i.e., the clear command), I get something like this instead:

oopsy# clear
ld.so.1: clear: fatal: libncurses.so.5: open failed: No such file or
directory
Killed

Often, on encountering this problem, I simply growl, press enter a couple dozen times and continue working. When I'm in a particularly "fixit" mood, on the other hand, I figure I shouldn't be putting up with annoying configuration problems and decide to break my train of thought just long enough to tackle this distracting problem head-on. Here's what you can do when you get an error such as this.

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Windows Tip: Shrinking XP partitions using diskpart

By Mitch Tulloch, MTIT Enterprises

The version of the diskpart command included in Windows Vista allows you to shrink partitions to free up space on your hard drive so you can create additional partitions. Unfortunately, the version of diskpart included in Windows XP doesn't include this functionality, so the usual way of shrinking XP partitions is to use a third-party tool like Symantec's Norton PartitionMagic.

If you have a Windows Vista product DVD around however, you can use Vista's version of diskpart to shrink partitions on a computer that has Windows XP installed. To accomplish this bit of magic, do the following:

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Unix Tip: Using fuser to determine why a file system is busy

By Sandra Henry-Stocker

The fuser command can save you a lot of time when you need to quickly determine how a file system or a particular file is being used, particularly when you cannot unmount a file system due to current usage. The script in this article provides more information on the processes keeping a file system busy by using fuser to supply process IDs to ps and ps to then display additional information about each process. Read more.

Windows Tip: Disabling system tasks

By Mitch Tulloch, MTIT Enterprise

Ever had a scheduled task on your computer that you can't disable or configure? This can happen if an application running under the built-in SYSTEM account creates the task, and even if you are logged on as the local administrator, you may not be able to configure the task. If you find yourself in this situation, try doing the following.

Unix Tip: Finding services on a subnet

By Sandra Henry-Stocker, ITworld.com

Part 1 of this tip looks at how nmap, the well known port mapper, can be used to help monitor applications and services on a network or subnet with very little overhead and surprisingly little effort. Part 2 enhances the findAppl script to include the system name for each line of output.

Windows Tip: Clustered DHCP Servers

By Mitch Tulloch, MTIT Enterprises

DHCP servers are at the heart of network client availability, and I've seen administrators bend over backwards trying to build some sort of high-availability solution that can kick in when their main DHCP server fails. And believe me, seeing your average administrator try to bend over backwards isn't a pretty sight.

One company I heard about recently apparently does the following: They have two DHCP servers configured with identical scopes, but one of the servers (we'll call it the fallback) has its scopes deactivated. The administrator created a netsh script that is scheduled to run periodically on the main server and which first backs up this server's DHCP configuration and then restores the configuration onto the fallback server.

So is this a good idea? Probably not.

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Unix Tip: Sendmail gets smarter

By Sandra Henry-Stocker, ITworld.com

Before sendmail 8.13, sendmail servers were generally set up in one of two ways. Either their configurations were based on the main.cf file and they used DNS MX records to determine the identities (and IP addresses) of hosts to which mail was to be delivered or their configuration was based on the subsidiary.cf file and they were set up to relay mail through a system with more knowledge of the outside world (in particular, access to a real world DNS server) than systems requiring the relay service.

These two basic configurations have basically merged in version 18.13 of the sendmail software with the addition of a new configuration option -- the FallbackSmartHost.

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