Jul 032011
A “Poor Man’s Load Balancer” is just publishing multiple DNS records for the same resource. However, it doesn’t really work, and it certainly doesn’t work the way novices expect it to. The publishing DNS server can give them in any order, or it may give them in a specific order, or it might give different result sets to different clients, or any intervening caching server my truncate or reorder results, or your client OS may want to sort result sets its own way, or your application may cache and sort its own results. Different resolver libraries handle results differently, and you can get different results by which function your application calls (getaddrinfo? gethostbyname? IPv4 or IPv6?).
Relevant links
- Why DNS Based Global Server Load Balancing (GSLB) Doesnt Work
- Overview of DNS Caching In Browsers – Addendum to Why DNS Based GSLB Doesnt Work
- ‘Re CVS cvs.openbsd.org src’ – MARC
- Bug#340514 marked as done (libc6 dns resolver sort ip address list)
- DNS Round Robin and Destination IP address selection – Microsoft Enterprise Networking Team – Site Home – TechNet Blogs
- DNS Shuffle Records and Round-Robin (DNS RR) Chapter 12. Designing for High Availability Integrated cisco and unix network architectures Networking eTutorials.org
- FGA The uselessness of Round Robin resource record set shuffling
- djbdns – How to balance load among many web servers
- Re [TLS] Server Name Indication (SNI) in an IPv6 world
- resolv.conf(5) resolver config file – Linux man page
- test the round robin DNS features of the resolver functions ยป KutuKupret
- What is DNS round robin and subnet prioritization
- Windows Vista and Windows Server 2008 DNS clients do not honor DNS round robin by default
- Mark Minasi’s Reader Forum – DNS resolution order
- Mark Minasi’s Reader Forum – Name Resolution Order
- DNS balancing
- BIND’s rrset-order statement
- How Internet Explorer uses the cache for DNS host entries
- How to Disable Client-Side DNS Caching in Windows XP and Windows Server 2003
- BIND 9.4 Manual – Load Balancing
Sorry, the comment form is closed at this time.