Relevant example : two public-facing dns servers, on one vm host, vm host put into maintenance mode for updates, slow to no loading from those inside our network going out - we moved one to another vm host - lol
Sent from my iPhone On Jan 13, 2011, at 3:48 PM, Tim Holloway <[email protected]> wrote: > 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] > --------------------------------------------------------------------- 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]
