There are many reasons for this. It's just like saying why is RAID better when a flood is going to take out the whole raid array? There is still value in the redundancy, but the amount of value can be argued.
Also, when referring to a server having the DNS hosted on the same server as the website itself... Well, it's not unheard of for a single daemon to go down and the other to remain unaffected until a problem is rectified. While I agree the redundancy can be a bit silly at times, having multiple DNS options is important, especially when the average PC user cannot troubleshoot DNS issues. Me personally, I think it makes sense, but it's not of major importance. The more separation they have the better, for example first level of separation would be on 2 different virtual servers on the same box, then 2 separate machines all together, then 2 separate machines on separate connections, then finally (and ideally) 2 diff servers on totally different connections in different geographical areas. DNS does take a while to propagate which is another value to redundancy On Wed, Jan 12, 2011 at 1:38 PM, William L. Thomson Jr. <[email protected]> wrote: > On Wed, 2011-01-12 at 13:29 -0500, Deny IP Any Any wrote: >> On Wed, Jan 12, 2011 at 1:12 PM, William L. Thomson Jr. >> <[email protected]> wrote: >> > I have never understood that for this reason alone. If you only have one >> > real server, who cares how many DNS servers you have. If that one server >> > is down/offline/unavailable, what good does multiple DNS servers do >> > anyone? >> >> *If* you only have one server, then you've already made lots of >> compromises with regard to business continuity, and one more case of >> lack of redundancy clearly doesn't bother you. > > Single servers are likely much more common than fully redundant > environments. I can't recall how many times I have called into a company > to hear their systems are down, unavailable, etc. At times major > financial institutions, who likely have redundancies in place. > >> > Not to mention one of the simplest, most straight forward, and reliable >> > server services I have ever setup or worked with is DNS. It has never >> > made sense to me why you need two DNS servers, ideally on separate >> > networks. Now I do understand the importance of DNS in the general scope >> > of things. But again, if your servers are down, what good does a bunch >> > of DNS servers do you? >> >> What good does having a bunch of servers do you if your one-and-only >> DNS server has a hardware failure (or its NIC dies, or somebody >> unplugs it, or you are doing an 'apt-get update' on it, or somebody >> fat-fingers an ACL and blocks all packets to it, or BIND/kernel >> segfaults)? The idea is to make every link in the chain redundant if >> you really need high uptime, not just bits-n-pieces. > > Well I am not really advocating a single DNS server per se. But if you > only have a single server, then not sure what good having multiple DNS > servers really does you. Short of the scenarios mentioned in another > thread. > >> > Case in point, firebirdsql.org seems to be down atm. But they have a >> > whole bunch of DNS servers (~6) doing name to IP translation. Which >> > considering you can't get anything by hitting the single IP address all >> > 6 name servers serve up. Almost moot that you get an IP at all from DNS. >> >> This seems to be a case of having too much redundancy in certain >> areas, and clearly, not enough in others. > > Which I think is quite common, but I could be wrong. > > -- > William L. Thomson Jr. > Obsidian-Studios, Inc. > http://www.obsidian-studios.com > > > --------------------------------------------------------------------- > Archive http://marc.info/?l=jaxlug-list&r=1&w=2 > RSS Feed http://www.mail-archive.com/[email protected]/maillist.xml > Unsubscribe [email protected] > > --------------------------------------------------------------------- Archive http://marc.info/?l=jaxlug-list&r=1&w=2 RSS Feed http://www.mail-archive.com/[email protected]/maillist.xml Unsubscribe [email protected]
