2 Replies Latest reply: Apr 29, 2012 2:57 PM by TopCoder
tim_r_66 Level 1 Level 1 (45 points)

Good morning,


Set up:  I have  MacMini Server running 10.6 and three Mac clients (two with Snow Leopard and one with Lion).  All software updates are applied.  Two of the clients are connected with ethernet cable and one is connected over the Airport.  I use the server to provide DHCP for clients but one client uses a manual ip address.  I'm also running DNS with one primary zone for the server (basically).   Forwarder ip addresses are set to and recursive queries are accepted from "localnets".  This set up has been in place working for many months.  


Problem:  Yesterday morning, my wife, using her computer (one of the 10.6 clients), complained that her mail was not coming in.  We use Apple Mail to connect to Gmail using imap.  Mine continued to work fine even though the set up is basically the same but I use the Lion client.  There were not any problems browsing and she could get the mail through the Gmail web site, just not imap. 


Actions:  Through troubleshooting I determined the problem to be associated with DNS lookups of cname records.  Lookup of gmail-imap.l.google.com works fine, lookup of imap.gmail.com fails.


Tims-Mac-mini:Programming tim$ dig imap.gmail.com



; <<>> DiG 9.7.3-P3 <<>> imap.gmail.com

;; global options: +cmd

;; connection timed out; no servers could be reached



Tims-Mac-mini:Programming tim$ dig gmail-imap.l.google.com



; <<>> DiG 9.7.3-P3 <<>> gmail-imap.l.google.com

;; global options: +cmd

;; Got answer:

;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 6239

;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 4, ADDITIONAL: 0




;gmail-imap.l.google.com.          IN          A




gmail-imap.l.google.com. 231          IN          A

gmail-imap.l.google.com. 231          IN          A




google.com.                    98135          IN          NS          ns1.google.com.

google.com.                    98135          IN          NS          ns4.google.com.

google.com.                    98135          IN          NS          ns3.google.com.

google.com.                    98135          IN          NS          ns2.google.com.



;; Query time: 422 msec

;; SERVER: <local_DNS_server_ip>#53(<local_DNS_server_ip>)

;; WHEN: Sat Apr 28 07:14:17 2012

;; MSG SIZE  rcvd: 145


Initally, this behavior was only on the 10.6 clients but is now also present on the Lion client. 


I have used dscacheutil to flush the cache on clients and the server multiple times but it doesn't seem to help.


Yesterday afternoon, I threw up my hands and rebooted the server.  It worked (I thought) so I decided it was a mystery I would not understand. 


But, the problem returned last night.  A lookup of imap.gmail.com works from the server but not from any of the clients.


Does anyone know what is going on?  What can I test next?


Thank you in advance.



Mac mini, Mac OS X (10.6.8), Snow Leopard Server
  • tim_r_66 Level 1 Level 1 (45 points)

    Ok, I swear I did searches yesterday and this morning for similar problems without finding anything!  But, I guess posting something new helped bring like search terms together :-)


    I just found this post that describes a similar problem and puts the blame on VirtualBox.  I am running two VMs off the same server (10.6) described above.  Again, I have been running this set up for some time without issue.  The change I made was a few days ago regarding the network card of one of the VMs.  I'm going to play with that to see if I can get everything working again. 


    If anyone wants to weigh in with solutions, I'm happy to listen. 



  • TopCoder Level 1 Level 1 (0 points)

    It can be the DNS servers your pointing to, normally, I like to go against the SOA for the server to get the correct records..  Take a look here at the DNS for Imap.gmail.com  , as you can see it goes after ns1.google.com as the authority server. It returns two A records, gmail-imap.l.google.com , keep in mind if there are no MX records present then the "A" records are used.


    Of course you can do all these commands with DIG and get the SOA record and then go against that name server, but your right it is a little wierd that something is messed up. It might be a routing issue outside of your control.


    When I go against I get the same response that I get at the site linked in above.


    ; <<>> DiG 9.3.2 <<>> @ imap.gmail.com A

    ; (1 server found)

    ;; global options:  printcmd

    ;; Got answer:

    ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 4861

    ;; flags: qr rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 0



    ;imap.gmail.com.               IN     A



    imap.gmail.com.          300     IN     CNAME     gmail-imap.l.google.com.

    gmail-imap.l.google.com. 300     IN     A

    gmail-imap.l.google.com. 300     IN     A


    ;; Query time: 18 msec

    ;; SERVER:

    ;; WHEN: Sun Apr 29 23:55:16 2012

    ;; MSG SIZE  rcvd: 98