Date: Fri, 23 Oct 2009 11:12:10 -0400 From: DAve <dave.list@pixelhammer.com> To: 'User Questions' <freebsd-questions@freebsd.org> Subject: Re: DNS Question Message-ID: <4AE1C7CA.7030905@pixelhammer.com> In-Reply-To: <BAY126-W10FFB10639328D88BCE55CCABD0@phx.gbl> References: <4AE1A1D0.8060402@pixelhammer.com> <BAY126-W10FFB10639328D88BCE55CCABD0@phx.gbl>
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Sean Cavanaugh wrote: > > 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 <http://www.bobshosting.com>; A 192.168.0.1 > www.vhost1.com <http://www.vhost1.com>; CNAME > www.bobshosting.com <http://www.bobshosting.com>. > www.vhost2.com <http://www.vhost2.com>; CNAME > www.bobshosting.com <http://www.bobshosting.com>. > www.vhost3.com <http://www.vhost3.com>; CNAME > www.bobshosting.com <http://www.bobshosting.com>. > www.vhost4.com <http://www.vhost4.com>; CNAME > www.bobshosting.com <http://www.bobshosting.com>. > > > > -Sean All true, and I did not do a very good job of explaining it. My issue was that we have requests to use a CNAME for the domain record. Such as this. example.com CNAME otherdomain.com www.example.com CNAME otherdomain.com I was taught this was not good form, but allowed. I can deal with it. But what of having a SOA record for example.com, no A or CNAME record for the TLD example.com, only hosts such as www, ns1, ftp, etc. I tried it an it seems to work fine, but doesn't look proper to me. Then again I remember when CNAME were considered evil. DAve -- "Posterity, you will know how much it cost the present generation to preserve your freedom. I hope you will make good use of it. If you do not, I shall repent in heaven that ever I took half the pains to preserve it." John Quincy Adams http://appleseedinfo.org
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