Split-Brain DNS Clarification
I don’t claim to be a DNS expert, but I think Michael Dragone’s article—”Split- Brain DNS” (September 2008, InstantDoc ID 99772)—needs clarification. If a domain has sites that exist internally and externally and will have both internal and external users, you must have records on both the internal and external zones. Otherwise, internal queries for an external site that doesn’t exist in the internal zone will fail. The internal DNS server finds the zone locally, and when it doesn’t find the host you’re looking for, it gives up without forwarding up to a higher name server.
In the article, I assume that an external zone is already set up and that an internal zone is being added. Although it’s not specifically stated that you must add additional host records for your domain and not just a record for www (as the example shows), such is indeed the case. Note that these zones don’t have to—and likely won’t— identically match. Your internal zone is likely to resolve queries to private IP addresses instead of public IP addresses as your external one will, and you might not need all the host names in both. For example, there would be little need to resolve “remote vpnaccess.mydomain.com” internally.
Do We Really Want Dogfood?
Has it occurred to anyone that the phrase dogfooding (a vendor’s practice of using the same products it sells to customers) implies that the product is dogfood and that the customers are dogs? Maybe we should consult an oracle before we dream up more industry-standard terms ... or at least a common heckler.
I was dismayed to read Ken Spinks’s letter in the October 2008 edition of Windows IT Pro because it reinforced a common misconception about 64-bit systems. He writes that he bought a lesser PC for his wife because he “didn’t want extra (i.e., 64-bit related) problems with printers, scanners, cameras, or software.” The assumption is that 32-bit drivers will be more prevalent and better than their 64-bit counterparts. However, the exact opposite is true.
For Windows Vista logo certification, Microsoft required only 64-bit drivers, which means these were the only drivers that experienced the rigorous testing required for certification. My personal experience bears this out: My business laptop running the 64-bit version of Vista Ultimate works with all my peripherals and is far more stable and reliable than the 32-bit version of Vista Ultimate that I run on my home PC. Mr. Spinks could have still run a 32-bit version of Vista on the upscale PC that he passed over. PCs with 64-bit AMD or Intel processors are fully backward-compatible and will run either a 32-bit or 64-bit OS.
—Alan J. Walsh
Disabling Automatic SUA Startup?
I enjoyed John Howie’s “Move Apps from UNIX to Windows with SUA” (September 2008, InstantDoc ID 99588). I’m considering using the feature in Vista, but I’m curious whether Subsystem for UNIX-Based Applications (SUA) must start up with Windows. I’d like to disable automatic SUA startup at system startup and instead have it launch only when I run an SUA application. Can I do that?
SUA isn’t a traditional Windows service; it’s an optional subsystem, started when the system boots. In the days of Windows NT, both the OS/2 and POSIX subsystems shipped “in the box.” Now, POSIX is an optional extra. It’s configured in the HKEY_LOCAL_MACHINE SYSTEM\CurrentControlSet\Control\Session Manager\SubSystems\Option registry subkey (of type REG_MULTI_SZ and value Posix). If the registry entry is present, you’ll see another subkey (under the same key) called Posix, which contains the value %SystemRoot%\system32 psxss.exe. This is the POSIX subsystem executable, which runs at startup. There’s no support for starting it after the system has started.
I just want to commend Windows IT Pro on Robert Sheldon’s fantastic PowerShell series (“PowerShell 101,” February–July 2008). And you capped it off in September with the fivepage knockout “Managing AD User Accounts with PowerShell” (InstantDoc ID 99760). Articles like these are the reason I subscribe to your magazine.