To put it briefly, some of the most infamous big-name outages in the history of the Internet were blamed on DNS failures. Some of them probably even were DNS failures.
I ended up giving a free pass to my entire client base one month because I'd just had all my IP addresses changed - including the DNS servers - and gotten into a chicken-and-egg scenario. I always run at least 2 DNS servers. I have multiple boxes. If one goes down and it has a domain name server on it, the other boxes continue to be locatable via the other domain name server. Tim On Wed, 2011-01-12 at 15:30 -0500, Chad Bailey wrote: > 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] > --------------------------------------------------------------------- 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]
