Re: Can MX record be CNAME?
Markus Stumpf wrote: The funny thing about this whole thread is that the source of all problems is probably a lousy provider, that doesn't care for PTR delegations. So why don't you get yourself a caring one? Actually, they do care about them, but aren't that happy to make them. And I don't like to be dependent on them and would like to fix things myself. Here is another question to keep this hilarous thread alive: Is there any relationship with the MX record and qmail's control/me variable. If they are different, will it cause any trouble? I suppose not, but one can never be sure enough... Regards, Peter
Re: Can MX record be CNAME?
On Mon, May 07, 2001 at 11:04:52AM +0300, Peter Peltonen wrote: [snip] Here is another question to keep this hilarous thread alive: Please stop this thread. Is there any relationship with the MX record and qmail's control/me variable. If they are different, will it cause any trouble? I suppose not, but one can never be sure enough... There is no relation. This is a feature. Greetz, Peter.
Re: Can MX record be CNAME?
On Thu, May 03, 2001 at 08:16:16PM -0500, q question wrote: Actually, I think I could never have solved the sendmail configuration problems that I have solved without knowing BIND thoroughly. Mail administration maintenance doesn't need detailed BIND, but the initial sendmail configuration in a complex environment absolutely needs thorough DNS/BIND knowledge. STOP THIS OT Stuff! Mr. q question, I haven't seen a single on-topic post from you. Please search another communications forum for smalltalk. This List is not about sendmail, BIND or Flaming Charles, this list is about qmail, period. -- Henning Brauer | BS Web Services Hostmaster BSWS| Roedingsmarkt 14 [EMAIL PROTECTED] | 20459 Hamburg http://www.bsws.de | Germany Unix is very simple, but it takes a genius to understand the simplicity. (Dennis Ritchie)
Re: Can MX record be CNAME?
Aaron Goldblatt wrote: With respect to the remainder of your question, reverse resolution isn't a necessary consideration. For example: mail.goldblatt.net -- 208.190.130.82. It reverses to wndrgrl.goldblatt.net. It still works. This is the case what made me think the subject in the first place: If mail servers MX name (mail.goldblatt.net) which it announces when contacting another mailserver is different than the one that a PTR record for it's IP address 208.190.130.82 resolves (wndrgrl.goldblatt.net) I thought it might lead to trouble. But you are absolutely sure that it won't? If so, great, no problemo then. Peter
Re: Can MX record be CNAME?
On Thu, May 03, 2001 at 08:18:56PM -0500, q question wrote: Please stop this useless flaming. You aren't posting anything usefull, just flaming charles. This is a technical discussion list, no smalltalk. Either provide answers or participate in technical discussions or shut up. I am not flaming Charles in any way. I have been completely respectful. Sure. What else. I have requested that he not issue blanket directives that are not necessarily shared by all. You are posting tons of useless OFF TOPIC stuff and not a single on-topic message so far, please stop this NOW. -- Henning Brauer | BS Web Services Hostmaster BSWS| Roedingsmarkt 14 [EMAIL PROTECTED] | 20459 Hamburg http://www.bsws.de | Germany Unix is very simple, but it takes a genius to understand the simplicity. (Dennis Ritchie)
Re: Can MX record be CNAME?
* Henning Brauer [EMAIL PROTECTED] [010504 04:49]: [...] You are posting tons of useless OFF TOPIC stuff and not a single on-topic message so far, please stop this NOW. http://www.moongroup.com/stories.php?story=01/04/19/7271589 - nice site, too. And fix your sig. Noone's gonna call you with an MUA, you know? }:-
Re: Can MX record be CNAME?
q question [EMAIL PROTECTED] wrote: I was appalled when [Charles] said please don't post BIND zonefiles to Dan's lists. That is a blanket directive that is not necessarily shared by everyone on this list, certainly not me. directive request A few lines of zone records speaks volumes for BINDthinkers and they are well worth the space in the email. BINDthinkers are WRONGthinkers. djbdnsthinkers are RIGHTthinkers. :-) Zone files are as welcome here as sendmail.cf's: not very. DJB went to a great deal of effort to free us from crapware like Sendmail and BIND. Please show him a little respect. -Dave
Re: Can MX record be CNAME?
On Fri, May 04, 2001 at 11:14:52AM +0300, Peter Peltonen wrote: But you are absolutely sure that it won't? If so, great, no problemo then. You can't be sure about anything. There are broken DNS libraries out there, paranoid configured tcpservers/inetds/... The funny thing about this whole thread is that the source of all problems is probably a lousy provider, that doesn't care for PTR delegations. So why don't you get yourself a caring one? \Maex -- SpaceNet AG| Joseph-Dollinger-Bogen 14 | Fon: +49 (89) 32356-0 Research Development | D-80807 Muenchen| Fax: +49 (89) 32356-299 Stress is when you wake up screaming and you realize you haven't fallen asleep yet.
Re: Can MX record be CNAME?
temper, temper, Henning... my temper got me into trouble earlier this week... just let them act like children and let it go - hogan At 03:15 AM 5/4/2001, you wrote: On Thu, May 03, 2001 at 08:18:56PM -0500, q question wrote: Please stop this useless flaming. You aren't posting anything usefull, just flaming charles. This is a technical discussion list, no smalltalk. Either provide answers or participate in technical discussions or shut up. I am not flaming Charles in any way. I have been completely respectful. Sure. What else. I have requested that he not issue blanket directives that are not necessarily shared by all. You are posting tons of useless OFF TOPIC stuff and not a single on-topic message so far, please stop this NOW. -- Henning Brauer | BS Web Services Hostmaster BSWS| Roedingsmarkt 14 [EMAIL PROTECTED] | 20459 Hamburg http://www.bsws.de | Germany Unix is very simple, but it takes a genius to understand the simplicity. (Dennis Ritchie) _ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com
Re: Can MX record be CNAME?
From: Dave Sill [EMAIL PROTECTED] To: [EMAIL PROTECTED] Subject: Re: Can MX record be CNAME? Date: Fri, 4 May 2001 08:32:58 -0400 q question [EMAIL PROTECTED] wrote: I was appalled when [Charles] said please don't post BIND zonefiles to Dan's lists. That is a blanket directive that is not necessarily shared by everyone on this list, certainly not me. directive request A few lines of zone records speaks volumes for BINDthinkers and they are well worth the space in the email. BINDthinkers are WRONGthinkers. djbdnsthinkers are RIGHTthinkers. :-) Zone files are as welcome here as sendmail.cf's: not very. DJB went to a great deal of effort to free us from crapware like Sendmail and BIND. Please show him a little respect. -Dave I have shown respect for DJB and everyone on this list. I am looking very seriously at installing djbdns, and I'm sure that djbdns is in fact probably going to show itself to be superior to BIND. BINDthinkers cannot just jump blindly into djbdnsthink. There are going to be a few posts now and again where someone is going to show a few zone records to clarify their point while they transition into qmail/djbdns/etc. Noone should say: please don't post BIND zonefiles to Dan's lists. This fellow only showed a few lines, not his entire zonefile. I made one simple request to Charles not to shut down this kind of information and received arguments from Charles which I responded to. In the process of responding to the arguments generated by Charles, I have been accused wrongly of being off-topic. END OF DISCUSSION _ Get your FREE download of MSN Explorer at http://explorer.msn.com
Re: Can MX record be CNAME?
On Fri, May 04, 2001 at 01:19:17PM -0500, q question wrote: I have shown respect for DJB and everyone on this list. I am looking very seriously at installing djbdns, and I'm sure that djbdns is in fact probably going to show itself to be superior to BIND. Heh, it's funny how some people talk about respect and yet hide behind fake e-mail addresses and pseudonyms. --Adam
Re: Can MX record be CNAME?
q question [EMAIL PROTECTED] wrote: END OF DISCUSSION Sorry, q, but I'm not ready to end the discussion, despite your declaration. Dave Sill wrote: q question [EMAIL PROTECTED] wrote: I was appalled when [Charles] said please don't post BIND zonefiles to Dan's lists. That is a blanket directive that is not necessarily shared by everyone on this list, certainly not me. directive request You ignored this comment, which is, I think, critical. Charles said please don't post Charles did not say never post The former is a request. The latter is a directive. If Charles had given a directive, your reaction *might* have been justified. BINDthinkers cannot just jump blindly into djbdnsthink. There are going to be a few posts now and again where someone is going to show a few zone records to clarify their point while they transition into qmail/djbdns/etc. Such zone file excerpts should be prefaced with an apology. If no apology is included, offenders should not be surprised if people point out their faux pas. Noone should say: please don't post BIND zonefiles to Dan's lists. Who is Noone, and why should he repeat Charles' request? -Dave
RE: Can MX record be CNAME?
Everybody seriously needs to lighten up. A LOT.
Re: Can MX record be CNAME?
At 03:37 PM 5/4/2001 -0400, you wrote: BINDthinkers cannot just jump blindly into djbdnsthink. There are going to be a few posts now and again where someone is going to show a few zone records to clarify their point while they transition into qmail/djbdns/etc. Such zone file excerpts should be prefaced with an apology. If no apology is included, offenders should not be surprised if people point out their faux pas. -Dave Um guys... All I wanted to know was why you can't use CNAME for a MX record. The question has been answered, and maybe this topic can be dropped now? Or should we continue on giving our opinions on what should and shouldn't be posted and how it should be posted, etc... Second, I just wanted to point out that this is qmail list, not djdns or bind list. So asking a question related to qmail, and using a format of bind or djdns zone files to give further explanation of what is the question/problem should be ok. If bind zone files offend you, I think you might have a bigger problem to worry about. It's like saying inetd startup script for qmail offends me because I use tcpserver... Come on, give it a break. And giving an apology for posting relevant info? Maybe you should also put in an apology, every time you write something that might offend someone... The questions have been asked and answered, lets just move on with our lives now and end this thread. On an ending note, I appreciate everyone that responded to my question and gave me relevant info. I have fixed it on our servers, and am very happy that I am now RFC compliant. __ Kris.
Can MX record be CNAME?
I have a mail server with A record a.b.c and PTR record 1.2.3.4. The MX record says naturally a.b.c too. I want to change the servers dns name to mail.b.c. Unfortunately I do not control my PTR records so I have to do the dns name change with CNAME. My questions are: Can MX record point to a CNAME? Or maybe I should use multiple A records? In both cases, what do I put in /var/qmail/control/me? The same name as in the MX record? Peter
Re: Can MX record be CNAME?
Peter Peltonen [EMAIL PROTECTED] wrote: I have a mail server with A record a.b.c and PTR record 1.2.3.4. The MX record says naturally a.b.c too. I want to change the servers dns name to mail.b.c. This would have been easier if you'd used real names. However... Unfortunately I do not control my PTR records so I have to do the dns name change with CNAME. My questions are: Can MX record point to a CNAME? No, never. Or maybe I should use multiple A records? Yes. In both cases, what do I put in /var/qmail/control/me? The same name as in the MX record? Sure. Charles -- --- Charles Cazabon[EMAIL PROTECTED] GPL'ed software available at: http://www.qcc.sk.ca/~charlesc/software/ Any opinions expressed are just that -- my opinions. ---
Re: Can MX record be CNAME?
This would have been easier if you'd used real names. However... Charles, Why did you tell Peter this would have been easier if he had used real names? I found it very clear and frankly I prefer a.b.c and 1.2.3.4 to reading full domain names and ip numbers when the shorthand can convey the point clearly. _ Get your FREE download of MSN Explorer at http://explorer.msn.com
Re: Can MX record be CNAME?
This would have been easier if you'd used real names. However... Charles, Why did you tell Peter this would have been easier if he had used real names? I found it very clear and frankly I prefer a.b.c and 1.2.3.4 to reading full domain names and ip numbers when the shorthand can convey the point clearly. * * * | 1) It's SLOW!-- man tcpserver - especially -R,-H,-l qmail | 2) Roaming users -- http://www.lifewithqmail.org/lwq.html#relaying FAQS | 3) Secondary MX -- list in rcpthosts, NOT in locals/virtualdomains * * * | 4) Discard mail -- # line ONLY, in appropriate .qmail file _ Get your FREE download of MSN Explorer at http://explorer.msn.com
Re: Can MX record be CNAME?
q question [EMAIL PROTECTED] wrote: This would have been easier if you'd used real names. However... Why did you tell Peter this would have been easier if he had used real names? Because I believe that it would have been clearer if he had used real names? My eyes quickly get tired of trying to distinguish a.b.c and foo.b.c and foo.a.b.c, etc, etc... Charles -- --- Charles Cazabon[EMAIL PROTECTED] GPL'ed software available at: http://www.qcc.sk.ca/~charlesc/software/ Any opinions expressed are just that -- my opinions. ---
Re: Can MX record be CNAME?
On Thu, May 03, 2001 at 10:14:38AM -0500, q question wrote: Why did you tell Peter this would have been easier if he had used real names? I found it very clear and frankly I prefer a.b.c and 1.2.3.4 to reading full domain names and ip numbers when the shorthand can convey the point clearly. Because giving real information is *always* right. Giving mangled information is *rarely* right. james -- James Raftery (JBR54) It's somewhere in the Red Hat district -- A network engineer's freudian slip when talking about Amsterdam's nightlife at RIPE 38.
Re: Can MX record be CNAME?
What Charles said is totally correct, however I do not understand: On Thu, May 03, 2001 at 08:34:04AM -0600, Charles Cazabon wrote: Peter Peltonen [EMAIL PROTECTED] wrote: Unfortunately I do not control my PTR records so I have to do the dns name change with CNAME. What do - in this context - have PTR records to do with CNAMEs?? Just to make it clear, a MX record MAY NOT point to a CNAME nor to an A record, it always has to be a FQDN (which points to an A record). Speaking bind config it is invalid to have: blubb IN MX 100 1.2.3.4 blubb IN MX 100 mail mailIN CNAME exa exa IN A 1.2.3.4 \Maex -- SpaceNet AG| Joseph-Dollinger-Bogen 14 | Fon: +49 (89) 32356-0 Research Development | D-80807 Muenchen| Fax: +49 (89) 32356-299 Stress is when you wake up screaming and you realize you haven't fallen asleep yet.
Re: Can MX record be CNAME?
At 08:34 AM 5/3/2001 -0600, you wrote: Unfortunately I do not control my PTR records so I have to do the dns name change with CNAME. My questions are: Can MX record point to a CNAME? No, never. Charles, Why can't it be a CNAME? Is there a reason for this? I am currently using it as a CNAME and it's been working fine for a year or so... If there is a good reason for it, I sure would like to know so I can make changes. Thanks, __ Kris.
Re: Can MX record be CNAME?
Kris von Mach [EMAIL PROTECTED] wrote: Unfortunately I do not control my PTR records so I have to do the dns name change with CNAME. My questions are: Can MX record point to a CNAME? No, never. Why can't it be a CNAME? Because it is forbidden by the RFCs. Is there a reason for this? There are several technical reasons for this; read RFC2821 for some brief explanations, or possibly RFC821. Although I've read the recently released 2821, I do not specifically recall if they left that part of 821 in. Charles -- --- Charles Cazabon[EMAIL PROTECTED] GPL'ed software available at: http://www.qcc.sk.ca/~charlesc/software/ Any opinions expressed are just that -- my opinions. ---
Re: Can MX record be CNAME?
At 08:34 AM 5/3/2001 -0600, you wrote: Unfortunately I do not control my PTR records so I have to do the dns name change with CNAME. My questions are: Can MX record point to a CNAME? No, never. Charles, Why can't it be a CNAME? Is there a reason for this? I am currently using it as a CNAME and it's been working fine for a year or so... If there is a good reason for it, I sure would like to know so I can make changes. Oh I have this currently: IN NS ns1.webgoku.com. IN NS ns2.webgoku.com. IN MX 10 mail.swishmail.com. $ORIGIN swishmail.com. ; ; Setup forward DNS for all hosts IN A 63.165.246.3 www IN A 63.165.246.3 ftp IN CNAME swishmail.com. mailIN CNAME swishmail.com. Or did you mean that you can't have something like this: IN MX 10 mail IN A 63.165.246.3 www IN A 63.165.246.3 mailIN CNAME swishmail.com. Thanks, __ Kris.
Re: Can MX record be CNAME?
Kris von Mach [EMAIL PROTECTED] wrote: Can MX record point to a CNAME? No, never. Oh I have this currently: IN NS ns1.webgoku.com. IN NS ns2.webgoku.com. IN MX 10 mail.swishmail.com. $ORIGIN swishmail.com. ; ; Setup forward DNS for all hosts IN A 63.165.246.3 mailIN CNAME swishmail.com. Nope, mail.swishmail.com cannot be a CNAME if you want to point your MX record at it. It's forbidden. And please don't post BIND zonefiles to Dan's lists -- they're meaningless to anyone who doesn't do BINDthink. Instead, tell us what's happening (mail.foo.net is an MX record which points to mail.bar.org with distance 10, which has an A record of 10.20.30.40). That at least means something to everyone who understands a little about DNS. Charles -- --- Charles Cazabon[EMAIL PROTECTED] GPL'ed software available at: http://www.qcc.sk.ca/~charlesc/software/ Any opinions expressed are just that -- my opinions. ---
Re: Can MX record be CNAME?
On Thu, May 03, 2001 at 12:53:44PM -0400, Kris von Mach wrote: At 08:34 AM 5/3/2001 -0600, you wrote: Unfortunately I do not control my PTR records so I have to do the dns name change with CNAME. My questions are: Can MX record point to a CNAME? CC -- No, never. Charles, Why can't it be a CNAME? Is there a reason for this? I am currently using it as a CNAME and it's been working fine for a year or so... If there is a good reason for it, I sure would like to know so I can make changes. It's not actually a _violation_, as such, but RFC1034 (one of the DNS specification RFCs) says that: If a CNAME RR is present at a node, no other data should be present; this ensures that the data for a canonical name and its aliases cannot be different. This rule also insures that a cached CNAME can be used without checking with an authoritative server for other RR types. This means that pointing MX, NS, and SOA (at least) at a CNAME is not recommended. Personally, I hate CNAME, and I almost never use it. I can think of only one specialized use where CNAME comes in handy (third-party hosting). Nearly everything else can be done more efficiently with multiple A records IMHO. P.S. If someone has a reference to an RFC which says 'must not' rather than 'should not', I'll be happy to use it from now on. :)
Re: Can MX record be CNAME?
Charles and James, Some people may have private domains that they don't wish to disclose. These people are usually advanced enough to do a clear job with generic a.b.c notation. I agree that novices probably should stick to the full domain names because they are probably too confused to translate correctly into generic a.b.c notation. From: James Raftery [EMAIL PROTECTED] To: [EMAIL PROTECTED] Subject: Re: Can MX record be CNAME? Date: Thu, 3 May 2001 16:45:27 +0100 On Thu, May 03, 2001 at 10:14:38AM -0500, q question wrote: Why did you tell Peter this would have been easier if he had used real names? I found it very clear and frankly I prefer a.b.c and 1.2.3.4 to reading full domain names and ip numbers when the shorthand can convey the point clearly. Because giving real information is *always* right. Giving mangled information is *rarely* right. james -- James Raftery (JBR54) It's somewhere in the Red Hat district -- A network engineer's freudian slip when talking about Amsterdam's nightlife at RIPE 38. _ Get your FREE download of MSN Explorer at http://explorer.msn.com
Re: Can MX record be CNAME?
Nope, mail.swishmail.com cannot be a CNAME if you want to point your MX record at it. It's forbidden. And please don't post BIND zonefiles to Dan's lists -- they're meaningless to anyone who doesn't do BINDthink. Instead, tell us what's happening (mail.foo.net is an MX record which points to mail.bar.org with distance 10, which has an A record of 10.20.30.40). That at least means something to everyone who understands a little about DNS. 1) I appreciated Kris's short excerpt from his BIND zonefiles. They were exactly what I needed to see to understand what Kris was saying about his CNAMES. 2) I find the sentence format that describes what is happening mail.foo.net is an MX record which points to ... to be more confusing than seeing the exact records. 3) The people that don't do BINDthink aren't going to understand either the sentence format or the exact record layout. I think people either know or don't know DNS, and they don't fall into a middle ground that can be addressed by the sentence layout. 4) You have stated repeatedly that people must provide detailed information in their emails to this list. Kris did so, and you protest that it is too detailed. You really can't have it both ways. _ Get your FREE download of MSN Explorer at http://explorer.msn.com
Re: Can MX record be CNAME?
q question [EMAIL PROTECTED] wrote: Charles and James, Some people may have private domains that they don't wish to disclose. These people are usually advanced enough to do a clear job with generic a.b.c notation. Which is pointless. You can't receive mail without advertising the domain in the DNS, so trying to hide the information here achieves precisely nothing. Hiding the domain here just makes the job of list members tougher. I encourage everyone to ignore messages with falsified domain information or logs. Charles -- --- Charles Cazabon[EMAIL PROTECTED] GPL'ed software available at: http://www.qcc.sk.ca/~charlesc/software/ Any opinions expressed are just that -- my opinions. ---
Re: Can MX record be CNAME?
q question [EMAIL PROTECTED] wrote: And please don't post BIND zonefiles to Dan's lists -- [...] Instead, tell us [the contents of the DNS records] 4) You have stated repeatedly that people must provide detailed information in their emails to this list. Kris did so, and you protest that it is too detailed. You really can't have it both ways. I didn't mean don't give us the DNS information. I meant give us the DNS information in a format that does not require an intimiate knowledge of BIND zonefile format. After all, you don't need to know anything about BIND to be a knowledgable mail admin. You just need to understand some DNS basics. I, unfortunately, have had to learn a bit here and there about BIND zonefiles, but I still prefer the information in a non-proprietary format. BINDthink is painful, and in this list, completely unnecessary. Charles -- --- Charles Cazabon[EMAIL PROTECTED] GPL'ed software available at: http://www.qcc.sk.ca/~charlesc/software/ Any opinions expressed are just that -- my opinions. ---
Re: Can MX record be CNAME?
On Thu, May 03, 2001 at 02:04:55PM -0500, q question wrote: 3) The people that don't do BINDthink aren't going to understand either the sentence format or the exact record layout. I think people either know or don't know DNS, and they don't fall into a middle ground that can be addressed by the sentence layout. Knowing DNS does not necessary mean knowing BIND. qmail's autor has written a replacement using another (IMHO much better) format. Please stop this useless flaming. You aren't posting anything usefull, just flaming charles. This is a technical discussion list, no smalltalk. Either provide answers or participate in technical discussions or shut up. -- Henning Brauer | BS Web Services Hostmaster BSWS| Roedingsmarkt 14 [EMAIL PROTECTED] | 20459 Hamburg http://www.bsws.de | Germany Unix is very simple, but it takes a genius to understand the simplicity. (Dennis Ritchie)
Re: Can MX record be CNAME?
At 11:09 AM 5/3/2001 -0700, you wrote: This means that pointing MX, NS, and SOA (at least) at a CNAME is not recommended. Personally, I hate CNAME, and I almost never use it. I can think of only one specialized use where CNAME comes in handy (third-party hosting). Nearly everything else can be done more efficiently with multiple A records IMHO. So, having multiple A records pointing to the same IP is ok then, when it comes to MX? like this: IN MX 10 mail.swishmail.com. $ORIGIN swishmail.com. ; Setup forward DNS for all hosts IN A 63.165.246.3 www IN A 63.165.246.3 mailIN A 63.165.246.3 ftp IN A 63.165.246.3 pop3IN CNAME swishmail.com. Or should MX mail.swishmail.com point to an IP address that nothing else points to? like for example: IN MX 10 mail.swishmail.com. $ORIGIN swishmail.com. ; Setup forward DNS for all hosts IN A 63.165.246.3 www IN A 63.165.246.3 mailIN A 63.165.246.5 ftp IN A 63.165.246.3 pop3IN CNAME swishmail.com. The reason why I am asking is would mail.swishmail.com be considered FQDN with the first example? Since mail.swishmail.com would resolve to 63.165.246.3, but 63.165.246.3 would resolve to swishmail.com. With the second example, forward and reverse would give you mail.swishmail.com - 63.165.256.5 and 63.165.256.5 - mail.swishmail.com __ Kris.
Re: Can MX record be CNAME?
Kris von Mach [EMAIL PROTECTED] wrote: So, having multiple A records pointing to the same IP is ok then, when it comes to MX? Yes. Or should MX mail.swishmail.com point to an IP address that nothing else points to? like for example: No, not necessary. The reason why I am asking is would mail.swishmail.com be considered FQDN with the first example? Yes. Since mail.swishmail.com would resolve to 63.165.246.3, but 63.165.246.3 would resolve to swishmail.com. With the second example, forward and reverse would give you mail.swishmail.com - 63.165.256.5 and 63.165.256.5 - mail.swishmail.com That doesn't matter for SMTP. Why don't you try it and see? Charles -- --- Charles Cazabon[EMAIL PROTECTED] GPL'ed software available at: http://www.qcc.sk.ca/~charlesc/software/ Any opinions expressed are just that -- my opinions. ---
Re: Can MX record be CNAME?
On Thu, May 03, 2001 at 04:39:32PM -0400, Kris von Mach wrote: At 11:09 AM 5/3/2001 -0700, you wrote: This means that pointing MX, NS, and SOA (at least) at a CNAME is not recommended. Personally, I hate CNAME, and I almost never use it. I can think of only one specialized use where CNAME comes in handy (third-party hosting). Nearly everything else can be done more efficiently with multiple A records IMHO. So, having multiple A records pointing to the same IP is ok then, when it comes to MX? Yes. Or should MX mail.swishmail.com point to an IP address that nothing else points to? like for example: Not necessary. Greetz, Peter.
Re: Can MX record be CNAME?
On Thu, May 03, 2001 at 04:39:32PM -0400, Kris von Mach wrote: So, having multiple A records pointing to the same IP is ok then, when it comes to MX? like this: IN MX 10 mail.swishmail.com. $ORIGIN swishmail.com. ; Setup forward DNS for all hosts IN A 63.165.246.3 www IN A 63.165.246.3 mailIN A 63.165.246.3 ftp IN A 63.165.246.3 pop3IN CNAME swishmail.com. Or should MX mail.swishmail.com point to an IP address that nothing else points to? like for example: IN MX 10 mail.swishmail.com. $ORIGIN swishmail.com. ; Setup forward DNS for all hosts IN A 63.165.246.3 www IN A 63.165.246.3 mailIN A 63.165.246.5 ftp IN A 63.165.246.3 pop3IN CNAME swishmail.com. The reason why I am asking is would mail.swishmail.com be considered FQDN with the first example? Since mail.swishmail.com would resolve to 63.165.246.3, but 63.165.246.3 would resolve to swishmail.com. With the second example, forward and reverse would give you mail.swishmail.com - 63.165.256.5 and 63.165.256.5 - mail.swishmail.com Both are acceptable and are considered FQDNs. FQDNs are only required to point to IPs. It says nothing about the IP pointing back to the FQDN. -- - Timothy L. Mayo mailto:[EMAIL PROTECTED] Senior System Administrator The National Business Network Inc. localconnect(sm) http://www.localconnect.net/ The National Business Network Inc. http://www.nb.net/ One Monroeville Center, Suite 850 Monroeville, PA 15146 (412) 810- Phone (412) 810-8886 Fax
Re: Can MX record be CNAME?
So, having multiple A records pointing to the same IP is ok then, when it comes to MX? MX records are considered and resolved separately from A records. With respect to the remainder of your question, reverse resolution isn't a necessary consideration. For example: mail.goldblatt.net -- 208.190.130.82. It reverses to wndrgrl.goldblatt.net. It still works. One issue to consider, if you're using Bind, is future maintainability. Consider what might happen if you renumber your network. If you are using a.b.c.d notation in your MX record, you must remember to update that record in addition to all your A records. If you use mail.whatever.com in your MX record, you have only to update your A record, which makes it less likely that in the event of a renumber, you'll screw it up and cut off mail service for a week. The down side is that this approach must, of necessity, produces another lookup for the A record, which produces additional load on your name servers and network to carry the UDP traffic. ag
Re: Can MX record be CNAME?
On Thu, May 03, 2001 at 05:32:52PM -0500, Aaron Goldblatt wrote: If you use mail.whatever.com in your MX record, you have only to update your A record, which makes it less likely that in the event of a renumber, you'll screw it up and cut off mail service for a week. The down side is that this approach must, of necessity, produces another lookup for the A record, which produces additional load on your name servers and network to carry the UDP traffic. In most cases, no. With some minor quibbles, as long as the nameserver is authoritative for your domain (which it had better be!) and both records (the MX and the A) are known to the nameserver, the nameserver will provide the A record as glue when the MX is requested. Using djbdns, here is a query for mx records for my domain, catseye.net: $ dnsq mx catseye.net ns1.catseye.net 15 catseye.net: 152 bytes, 1+2+2+2 records, response, authoritative, noerror query: 15 catseye.net answer: catseye.net 86400 MX 10 mail.catseye.net answer: catseye.net 86400 MX 20 mail.whatwerks.com authority: catseye.net 172800 NS ns1.catseye.net authority: catseye.net 172800 NS ns1.whatwerks.com additional: mail.catseye.net 86400 A 64.34.131.193 additional: ns1.catseye.net 86400 A 64.34.131.193 See the additional records? That all came back in one query and, since I'm authoritative, the dns resolver library can trust the glue, which means you don't need a second query. Note that I'm *not* authoritative for my backup, whatwerks.com, so the nameserver didn't provide glue for mail.whatwerks.com. Tim -- * * * | 1) It's SLOW!-- man tcpserver - especially -R,-H,-l qmail | 2) Roaming users -- http://www.lifewithqmail.org/lwq.html#relaying FAQS | 3) Secondary MX -- list in rcpthosts, NOT in locals/virtualdomains * * * | 4) Discard mail -- # line ONLY, in appropriate .qmail file
Re: Can MX record be CNAME?
Which is pointless. You can't receive mail without advertising the domain in the DNS, so trying to hide the information here achieves precisely nothing. That's not true. I've dealt with plenty of internal corporate email situations that are not exposed to the internet email. Not all email goes out on the internet. Hiding the domain here just makes the job of list members tougher. I encourage everyone to ignore messages with falsified domain information or logs. I think everyone should be free to describe their situation using either generic a.b.c notation or valid domain addresses. Granted, if you are a novice, it is preferred that you use the valid domain addresses because you may incorrectly use the wrong generic addressing. * * * | 1) It's SLOW!-- man tcpserver - especially -R,-H,-l qmail | 2) Roaming users -- http://www.lifewithqmail.org/lwq.html#relaying FAQS | 3) Secondary MX -- list in rcpthosts, NOT in locals/virtualdomains * * * | 4) Discard mail -- # line ONLY, in appropriate .qmail file _ Get your FREE download of MSN Explorer at http://explorer.msn.com
Re: Can MX record be CNAME?
From: Charles Cazabon [EMAIL PROTECTED] To: [EMAIL PROTECTED] Subject: Re: Can MX record be CNAME? Date: Thu, 3 May 2001 14:10:23 -0600 q question [EMAIL PROTECTED] wrote: And please don't post BIND zonefiles to Dan's lists -- [...] Instead, tell us [the contents of the DNS records] 4) You have stated repeatedly that people must provide detailed information in their emails to this list. Kris did so, and you protest that it is too detailed. You really can't have it both ways. I didn't mean don't give us the DNS information. I meant give us the DNS information in a format that does not require an intimiate knowledge of BIND zonefile format. After all, you don't need to know anything about BIND to be a knowledgable mail admin. Actually, I think I could never have solved the sendmail configuration problems that I have solved without knowing BIND thoroughly. Mail administration maintenance doesn't need detailed BIND, but the initial sendmail configuration in a complex environment absolutely needs thorough DNS/BIND knowledge. You just need to understand some DNS basics. I, unfortunately, have had to learn a bit here and there about BIND zonefiles, but I still prefer the information in a non-proprietary format. BINDthink is painful, and in this list, completely unnecessary. Charles, I understand what it is like to be somewhat familiar with something but not thoroughly familiar. There are so many technical topics that it is impossible for all of us to maintain a full level of expertise in everything at all times. Even once one has mastered a particular topic, it is quite easy to become rusty after only a few weeks away from the topic. I understand that you are asking for the sentence explanation for those who are not into BINDthink. I think it is fine to ask for the sentence explanation and say this is helpful for those not into BINDthink. Please respect those people who do understand BINDthink and realize that it is instantly more clear to us to see the actual records rather than to suppress the display of the actual records on the email list. You do not own this email list. You are sharing this space with a lot of people who have a wide range of technical expertise in a wide range of topics. Just because you prefer something in one particular way, does not mean your opinion must dominate. I thought it was terrific when Kris showed the actual zone records. I'm happy if he wants to take the time to make a sentence summary of it to please you and others who may be hazy about DNS. I was appalled when you said please don't post BIND zonefiles to Dan's lists. That is a blanket directive that is not necessarily shared by everyone on this list, certainly not me. A few lines of zone records speaks volumes for BINDthinkers and they are well worth the space in the email. _ Get your FREE download of MSN Explorer at http://explorer.msn.com
Re: Can MX record be CNAME?
I shall make no further comment.
