From owner-freebsd-questions@FreeBSD.ORG Fri Oct 23 12:49:38 2009 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 3EC92106566B for ; Fri, 23 Oct 2009 12:49:38 +0000 (UTC) (envelope-from m.seaman@infracaninophile.co.uk) Received: from smtp.infracaninophile.co.uk (gate6.infracaninophile.co.uk [IPv6:2001:8b0:151:1::1]) by mx1.freebsd.org (Postfix) with ESMTP id CB46C8FC13 for ; Fri, 23 Oct 2009 12:49:37 +0000 (UTC) Received: from happy-idiot-talk.infracaninophile.co.uk (localhost [IPv6:::1]) (authenticated bits=0) by smtp.infracaninophile.co.uk (8.14.3/8.14.3) with ESMTP id n9NCnQNe088988; Fri, 23 Oct 2009 13:49:32 +0100 (BST) (envelope-from m.seaman@infracaninophile.co.uk) X-DKIM: Sendmail DKIM Filter v2.8.3 smtp.infracaninophile.co.uk n9NCnQNe088988 DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=infracaninophile.co.uk; s=200708; t=1256302173; bh=S8f4antARN7kbcwkJOCDyxJaKoFS694ApjzZoIRtjp8=; h=Message-ID:Date:From:MIME-Version:To:CC:Subject:References: In-Reply-To:Content-Type:Cc:Content-Type:Date:From:In-Reply-To: Message-ID:Mime-Version:References:To; z=Message-ID:=20<4AE1A64F.1000405@infracaninophile.co.uk>|Date:=20F ri,=2023=20Oct=202009=2013:49:19=20+0100|From:=20Matthew=20Seaman= 20|Organization:=20Infracaninophi le|User-Agent:=20Thunderbird=202.0.0.23=20(X11/20090823)|MIME-Vers ion:=201.0|To:=20DAve=20|CC:=20'User=20 Questions'=20|Subject:=20Re:=20DNS= 20Question|References:=20<4AE1A1D0.8060402@pixelhammer.com>|In-Rep ly-To:=20<4AE1A1D0.8060402@pixelhammer.com>|X-Enigmail-Version:=20 0.95.6|Content-Type:=20multipart/signed=3B=20micalg=3Dpgp-sha256=3 B=0D=0A=20protocol=3D"application/pgp-signature"=3B=0D=0A=20bounda ry=3D"------------enigD55BD1E905DA0180AD30608D"; b=V16g7r8FKfV0AwpXqbaZLbKe4GP5ojk3QmbqiRj2MkbmEN1d6P1dSN/rFEnLLEEnj 0AABCCJU8JJt9u6FQKwjXUxTuP/yWYDiVpH/47o47el5UvRa3Sp43JTN+btlMHAxRh 3RSTBqmmztCUkhDKdMsQooXdPgoPUkIPPjZ6w490= X-Authentication-Warning: happy-idiot-talk.infracaninophile.co.uk: Host localhost [IPv6:::1] claimed to be happy-idiot-talk.infracaninophile.co.uk Message-ID: <4AE1A64F.1000405@infracaninophile.co.uk> Date: Fri, 23 Oct 2009 13:49:19 +0100 From: Matthew Seaman Organization: Infracaninophile User-Agent: Thunderbird 2.0.0.23 (X11/20090823) MIME-Version: 1.0 To: DAve References: <4AE1A1D0.8060402@pixelhammer.com> In-Reply-To: <4AE1A1D0.8060402@pixelhammer.com> X-Enigmail-Version: 0.95.6 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="------------enigD55BD1E905DA0180AD30608D" X-Virus-Scanned: clamav-milter 0.95.2 at happy-idiot-talk.infracaninophile.co.uk X-Virus-Status: Clean X-Spam-Status: No, score=-3.0 required=5.0 tests=AWL,BAYES_00,DKIM_SIGNED, DKIM_VERIFIED,NO_RELAYS autolearn=ham version=3.2.5 X-Spam-Checker-Version: SpamAssassin 3.2.5 (2008-06-10) on happy-idiot-talk.infracaninophile.co.uk Cc: 'User Questions' Subject: Re: DNS Question X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 23 Oct 2009 12:49:38 -0000 This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigD55BD1E905DA0180AD30608D Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable DAve wrote: > Good morning. >=20 > I have been asked by my co-workers and sales why I always create a A=20 > record for new domains we host instead of a CNAME. >=20 > The issue I run into lately with some domains is that a client has a=20 > 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=20 > client does not want an A record for frank.com. >=20 > Somewhere, in a class far far away, I was taught a DNS zone had to have= =20 > a A record to function properly. I can't seem to locate anything in the= =20 > RFCs. >=20 > Am I wrong? Yes, you're wrong. In terms of web service, you can use either an A record or a CNAME record= to provide the address part of a site's URL[*]. As far as the web server= is concerned, it looks for the 'Host=3D' line in the HTTP packet to decide w= hat name-based VHOST to dispatch the query to internally, and doesn't necessa= rily do any DNS lookups at all. Web clients just do a gethostbyname(3) or get= addrinfo(3) call to resolve the site name into an IP, and anything suppo= rted by those (/etc/hosts, NIS, LDAP, DNS) will do the trick. In terms of the DNS a 'Zone' is a delegated block of the name space under= a single administrative control. Typically with BIND this maps onto a si= ngle 'Zone file' containing all of the DNS resource records for the zone. The= only records a zone *has* to have are: * 1 SOA record, with the zone serial number * Some number of NS records giving the nameservers for the zone. It's perfectly permissible to have a zone that doesn't contain any A records (or AAAA records) and in fact, reasonably common: reverse domains= generally contain mostly PTR records.=20 Cheers, Matthew [*] Possibly others, but A and CNAME are the vast majority. Being able t= o use SRV for webservers would be cool. --=20 Dr Matthew J Seaman MA, D.Phil. 7 Priory Courtyard Flat 3 PGP: http://www.infracaninophile.co.uk/pgpkey Ramsgate Kent, CT11 9PW --------------enigD55BD1E905DA0180AD30608D Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.13 (FreeBSD) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iEYEAREIAAYFAkrhplYACgkQ8Mjk52CukIyFsgCeI7sHpEnPeFHGWyk7cXYtEK2r 4NkAoIjt3o8YeWlKbjQ1vsYvRCOBOsxJ =1xjM -----END PGP SIGNATURE----- --------------enigD55BD1E905DA0180AD30608D--