Date: Fri, 23 Oct 2009 10:22:50 -0400 From: Sean Cavanaugh <millenia2000@hotmail.com> To: "freebsd-questions@freebsd.org" <freebsd-questions@freebsd.org> Subject: FW: DNS Question Message-ID: <BAY126-W8642EA12C68270F81DA77CABD0@phx.gbl> In-Reply-To: <4AE1A1D0.8060402@pixelhammer.com> References: <4AE1A1D0.8060402@pixelhammer.com>
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> Date: Fri, 23 Oct 2009 08:30:08 -0400 > From: dave.list@pixelhammer.com > To: freebsd-questions@freebsd.org > Subject: DNS Question > > Good morning. > > I have been asked by my co-workers and sales why I always create a A > record for new domains we host instead of a CNAME. > > The issue I run into lately with some domains is that a client has a > website with a industry host such as frank.relator.com and he wants to > have DNS point www.frank.com to frank.relator.com with a CNAME. The > client does not want an A record for frank.com. > > Somewhere, in a class far far away, I was taught a DNS zone had to have > a A record to function properly. I can't seem to locate anything in the > RFCs. > > Am I wrong? > I think you are confusing basics of DNS records. you are partially correct in that a DNS zone needs an initial A record to be able to translate a name to an IP, but there is nothing wrong about setting up a CNAME to point to a record in a different zone instead. you just cannot do a zone that has a CNAME only that does not at some point to a valid A record. CNAMEs are forwarders only whereas A records are actual lookups. for proper way to set this up.... The A record would be assigned for the main name that you want to associate to an IP address. The CNAME record just relates a different name to that original name. this allows you to change the IP address of the server and only have to update the original A record instead of every DNS record for that server. for small number of vhosts, this would not really be an issue, but imagine if you were hosting a couple hundred vhosts from a single IP and then had to change that IP because you switched your ISP. It would take you a LONG time to update them if they were all A records, but only a couple of seconds if you had it properly set up as CNAME's www.bobshosting.com A 192.168.0.1 www.vhost1.com CNAME www.bobshosting.com. www.vhost2.com CNAME www.bobshosting.com. www.vhost3.com CNAME www.bobshosting.com. www.vhost4.com CNAME www.bobshosting.com. -Sean
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