Network diversity Software diversity
Although several people have leaped on the apparent lack of network diversity in Microsoft name servers, there is a more general problem which also affects networks using BIND. Using FreeBSD and BIND on *ALL* your name servers may be just as bad a practice as using Windows 2000 and Microsoft DNS on *ALL* your name servers. I still think NSI is taking a tremendous risk using identical servers for all their GTLD-servers, even though they are geographically distributed. You might try using UltraDNS on half your critical nameservers and BIND on the other half. And even using Solaris on some of the boxes and AIX or Linux, or NetBSD on the others. This is not because I think one or the other has a fatal flaw, but because software is a hard beast to manage. The idea behind diversity isn't you will never have an error. But the errors are unlikely to strike both servers at the same time. If you use identical servers and identical software, no matter how geopgrahically dispersed, a software flaw will affect all your servers at the same time. Software is what crashed the ATT long distance network, the Worldcom frame-relay network, and even the one incident which took out the entire ARPANET.
On 24 Jan 2001, Sean Donelan wrote: > Using FreeBSD and BIND on *ALL* your name servers may be just as > bad a practice as using Windows 2000 and Microsoft DNS on *ALL* > your name servers. You might try... using Solaris on some of the > boxes and AIX or Linux, or NetBSD on the others. Agreed. The Nominum GNS service is still using BIND code everywhere for the moment, but it's on heterogenous platforms, anyway... Every location has both Solaris-on-Sparc and NetBSD-on-Intel. I think they have a free or cheap way of using their network as secondaries, to try it out. That might be a good way to start. -Bill
[ On , January 24, 2001 at 17:19:29 (-0800), Sean Donelan wrote: ]
Subject: Network diversity Software diversity
Using FreeBSD and BIND on *ALL* your name servers may be just as bad a practice as using Windows 2000 and Microsoft DNS on *ALL* your name servers. I still think NSI is taking a tremendous risk using identical servers for all their GTLD-servers, even though they are geographically distributed.
Yeah, I was going to mention that, but I thought I'd already been preaching too much to the converted! :-)
You might try using UltraDNS on half your critical nameservers and BIND on the other half. And even using Solaris on some of the boxes and AIX or Linux, or NetBSD on the others. This is not because I think one or the other has a fatal flaw, but because software is a hard beast to manage. The idea behind diversity isn't you will never have an error. But the errors are unlikely to strike both servers at the same time.
Therein lies the rub -- adding extra complexity to your systems also makes them more difficult to manage, prone to error, and subject to interoperational problems. Diversity of all forms definitely has its advantages, but it has its costs too. The trick is to find a fair balance. :-) -- Greg A. Woods +1 416 218-0098 VE3TCP <gwoods@acm.org> <robohack!woods> Planix, Inc. <woods@planix.com>; Secrets of the Weird <woods@weird.com>
participants (3)
-
Bill Woodcock -
Sean Donelan -
woods＠weird.com