Remove/add [A] records based upon server availability

Mark Andrews marka at
Mon Dec 28 01:36:22 UTC 2009

In message <12831C89-2438-4A84-B81F-14A2ED000DDF at>, Chris Buxton 
> On Dec 27, 2009, at 7:16 AM, Rick Dicaire wrote:
> > On Sun, Dec 27, 2009 at 3:16 AM, Ryan S <ryan332211 at> wrote:
> >> Some web browers and applications will fail in a round-robin A record
> >> configuration such that if the first A record returned is unavailable, the
> n
> >> the browser will not bring up the page.
> > 
> > So fix the application instead of bending the protocol to suit a
> > broken applications need?
> > Specifically, what web browsers and applications are you referring to?
> > On what OS's?
> All web browsers, pretty much. Round robin does not provide failover except f
> or protocols and applications that specifically make it work, such as the DNS
>  and SMTP protocols (only between servers, in each case).
> Using DDNS to remove unresponsive or overloaded web servers from the rrset wo
> rks OK in situations where solutions at the HTTP and routing layers are not a
> ppropriate, such as web servers in different physical locations; there are ap
> pliance vendors out there offering such solutions. This is also similar to on
> e part of the Akamai solution for global traffic management.
> However, this strategy should be avoided when possible, and buffered with hig
> hly available solutions at each point to minimize the use.
> Chris Buxton
> Professional Services
> Men & Mice

Applications that fail to try multiple address are broken.  RFC 1123
said as much back in October 1989 (over twenty years ago now).  With
IPv6 coming along almost every host will be multihomed and if a
application doesn't cope then you should report it to the vendor now.
> _______________________________________________
> bind-users mailing list
> bind-users at
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka at

More information about the bind-users mailing list