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Thread: Question About Multiple DNS Entries

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  1. #1
    smpoole7 Guest

    Default Question About Multiple DNS Entries

    We have a legacy system that I inherited. Like most such systems, it has grown over the years to include a hotch-potch of scattered stuff and workarounds. We're trying to fix that with Zimbra. If one of you gurus could help me wrap my brain around this, I'd appreciate it. I'll try to be brief, but that's going to be hard to do. I apologize in advance. Here's what we've got:

    Primary domain: crawfordbroadcasting.com.
    Several mail-handling subs: smtp., pop., imaps., and barracuda.crawfordbroadcasting.com, all of which point to the same IP address.

    Most mail is "[user-name]@crawfordbroadcasting.com". We have several other domains for individual radio stations; ex., power92chicago.com, wmuz.com, etc. These have users, too, just not as many.

    The public MX records for ALL mail point to barracuda.crawfordbroadcasting.com. So whether you write "hotjock@power92chicago.com" or "reception-person@wmuz.com", from public DNS, the MX record is barracuda.crawfordbroadcasting.com. (A legacy from when we had a Barracuda Spam filter on a separate IP address for incoming SMTP.)

    I'm getting odd errors in the admin console when I click on a domain. From searching the forum, people are sent to the Split DNS article. Makes sense. Inside Webmail, our users from each domain can send to one another. But from the outside world, they can't send (but can receive). Ergo, I think it's still a DNS (and specifically, MX) issue.

    From the outside world, for example:

    Code:
    stephen@linux-clmk:~> host crawfordbroadcasting.com
    crawfordbroadcasting.com has address 173.8.230.33
    crawfordbroadcasting.com mail is handled by 0 barracuda.crawfordbroadcasting.com.
    stephen@linux-clmk:~> host barracuda.crawfordbroadcasting.com
    barracuda.crawfordbroadcasting.com has address 216.180.115.25
    stephen@linux-clmk:~> host smtp.crawfordbroadcasting.com
    smtp.crawfordbroadcasting.com has address 216.180.115.25
    stephen@linux-clmk:~> host pop.crawfordbroadcasting.com
    pop.crawfordbroadcasting.com has address 216.180.115.25
    The IP addresses are the correct public-side values (the reason we have so many different mail-related subdomain names is another legacy. These used to point to separate IP addresses.) Now, move onto the Zimbra server

    Code:
    [root@mail etc]# cat hosts
    127.0.0.1               localhost.localdomain localhost
    ::1             localhost6.localdomain6 localhost6
    192.168.1.250   mail.crawfordbroadcasting.com mail
    192.168.1.250   barracuda.crawfordbroadcasting.com barracuda
    
    [root@mail etc]# cat resolv.conf
    nameserver 127.0.0.1
    nameserver 216.180.122.2
    nameserver 216.180.99.2
    SSH into the mail server; check a few items (remember, I've got dnsmasq spoofing the MX records on the server itself):

    Code:
    [root@mail etc]# host wmuz.com
    wmuz.com has address 64.202.189.170
    wmuz.com mail is handled by 10 mail.crawfordbroadcasting.com.
    [root@mail etc]# host power92chicago.com
    power92chicago.com has address 67.72.16.137
    power92chicago.com mail is handled by 10 mail.crawfordbroadcasting.com.
    [root@mail etc]# host crawfordbroadcasting.com
    crawfordbroadcasting.com has address 173.8.230.33
    crawfordbroadcasting.com mail is handled by 10 mail.crawfordbroadcasting.com.
    
    [root@mail ~]# host mail.crawfordbroadcasting.com
    mail.crawfordbroadcasting.com has address 192.168.1.250
    [root@mail ~]# host barracuda.crawfordbroadcasting.com
    barracuda.crawfordbroadcasting.com has address 192.168.1.250
    Since the support folks here always ask for it, here are the digs for the three domains that I'm using as examples. These are done ON the mail server via SSH, so this is what dnsmasq is returning. Looks right to me.

    Code:
    [root@mail etc]# dig crawfordbroadcasting.com any
    
    ; <<>> DiG 9.3.6-P1-RedHat-9.3.6-20.P1.el5 <<>> crawfordbroadcasting.com any
    ;; global options:  printcmd
    ;; Got answer:
    ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 14117
    ;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1
    
    ;; QUESTION SECTION:
    ;crawfordbroadcasting.com.      IN      ANY
    
    ;; ANSWER SECTION:
    crawfordbroadcasting.com. 0     IN      MX      10 mail.crawfordbroadcasting.com.
    
    ;; ADDITIONAL SECTION:
    mail.crawfordbroadcasting.com. 0 IN     A       192.168.1.250
                                                                                                                                                                                            
    ;; Query time: 0 msec                                                                                                                                                                   
    ;; SERVER: 127.0.0.1#53(127.0.0.1)                                                                                                                                                      
    ;; WHEN: Sat Mar 31 22:08:50 2012                                                                                                                                                       
    ;; MSG SIZE  rcvd: 103                                                                                                                                                                  
                                                                                                                                  [root@mail etc]# dig wmuz.com any
                                                                                                                     
    ; <<>> DiG 9.3.6-P1-RedHat-9.3.6-20.P1.el5 <<>> wmuz.com any                                                                                                                            
    ;; global options:  printcmd                                                                                                                                                            
    ;; Got answer:                                                                                                                                                                          
    ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 57818                                                                                                                               
    ;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1
    
    ;; QUESTION SECTION:
    ;wmuz.com.                      IN      ANY
    
    ;; ANSWER SECTION:
    wmuz.com.               0       IN      MX      10 mail.crawfordbroadcasting.com.
    
    ;; ADDITIONAL SECTION:
    mail.crawfordbroadcasting.com. 0 IN     A       192.168.1.250
    
    ;; Query time: 0 msec
    ;; SERVER: 127.0.0.1#53(127.0.0.1)
    ;; WHEN: Sat Mar 31 22:09:02 2012
    ;; MSG SIZE  rcvd: 87
    
    [root@mail etc]# dig power92chicago.com any
    
    ; <<>> DiG 9.3.6-P1-RedHat-9.3.6-20.P1.el5 <<>> power92chicago.com any
    ;; global options:  printcmd
    ;; Got answer:
    ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 11906
    ;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1
    
    ;; QUESTION SECTION:
    ;power92chicago.com.            IN      ANY
    
    ;; ANSWER SECTION:
    power92chicago.com.     0       IN      MX      10 mail.crawfordbroadcasting.com.
    
    ;; ADDITIONAL SECTION:
    mail.crawfordbroadcasting.com. 0 IN     A       192.168.1.250
    
    ;; Query time: 0 msec
    ;; SERVER: 127.0.0.1#53(127.0.0.1)
    ;; WHEN: Sat Mar 31 22:09:10 2012
    ;; MSG SIZE  rcvd: 97
    I wonder if the fact that outside users are given "barracuda" instead of "mail" for the MX subdomain is the problem? What say the gurus?

    Running 6.0.15_GA on Centos 5.8, Dell Poweredge dual-processors with 8 gig of RAM.

  2. #2
    phoenix is offline Zimbra Consultant & Moderator
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    Default

    Quote Originally Posted by smpoole7 View Post
    I wonder if the fact that outside users are given "barracuda" instead of "mail" for the MX subdomain is the problem?.
    Whatever the 'outside' users use for a url should make no difference. You need to look in the log files and see what errors are there. You also need to fix the resolv.conf & /etc/hosts file - details of the required contents are in the 'Verify....' section of the Split DNS article, you can also run all the commands in that section again to check your LAN DNS configuration.

    Your external DNS records are, to some extent, a red herring with regards to this problem, as long as they all point to the mail server IP then there should be no problem. The likelihood is that it's a problem with either the hosts file and/or the resolv.conf - they both need fixing.
    Regards


    Bill


    Acompli: A new adventure for Co-Founder KevinH.

  3. #3
    smpoole7 Guest

    Default

    No, the hosts and resolv.conf were correct. I had forgotten to change the IP address in the "trusted MTA" configuration when I moved the mailstore from the old server to the new.

    She happy now. I can even send email to gmail and yahoo, so I can die happy.

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