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Can using a bare domain as server address (i.e. using example.com not www.example.com) make DNS based load balancing harder in some manner?

Load balancing examples:

Background: Sometimes when people argue one should include www in the server address, instead of using a bare domain name as server address, they mention problems related to load balancing and bare domains. But they don't seem to specify what are those problems.

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The only time you'll get problems is when you're using a third-party shared (or provider-managed GLB) load-balancing service, like Amazon's ELB, that requires you to put a CNAME to their load-balancing system into your DNS. In that case, you won't be able to use your bare domain name, because you can't have a CNAME and another record type (such as NS or SOA) on the same rrname.

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  • Interesting, I currently have a single Amazon EC2 instance. I suppose then that I'd better go with www, since in the future I'll probably use Amazon's Elastic Load Balancing.
    – KajMagnus
    Aug 29, 2011 at 13:10
  • This CNAME issue might actually be a rather huge problem for some people. Here is a terribly long thread discussing the issue with Amazon's ELB and (no) bare domains. In the thread, dafaleiting says that "The top 10 sites on the Internet according to Alexa are: Google, Facebook, YouTube, Yahoo, Live, Baidu, Wikipedia, Blogger, Twitter, and MSN. Of those ten, eight will redirect queries made to their DNS root to www.company.com. Only Twitter and Baidu actually serve requests off the root DNS."
    – KajMagnus
    Aug 29, 2011 at 15:42
  • It seems Amazon has a solution: Amazon [...] has [...] in order to easily let you map your root domain (e.g., mydomain.com, without the ‘www’), directly to your Load Balancer., see: forums.aws.amazon.com/ann.jspa?annID=1033
    – KajMagnus
    Aug 29, 2011 at 16:07
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    Amazon are probably doing shady-buggers with making an internal mapping between whatever IP your ELB has and your domain. This will only work if you're using both Route 53 and ELB. It doesn't help in the general case.
    – womble ♦
    Aug 29, 2011 at 18:11
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No, this will not make DNS load balancing any different. In both cases you must specify the round-robin entries in your zone file. Having www or '@' is a trivial difference.

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  • Okay, interesting to know that you can have many @ records (I was wondering if one could only have e.g. many www records), thanks.
    – KajMagnus
    Aug 30, 2011 at 14:37

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