Ajcody-Hostname-DNS
 - This article is NOT official Zimbra documentation. It is a user contribution and may include unsupported customizations, references, suggestions, or information.
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Hostname And DNS Issues
Actual Hostname And DNS Issues Homepage
Please see Ajcody-Hostname-DNS
Hostname resolution issues and testing commands
Allot of failed installs are because administrators are skipping the steps to make sure resolution is working.
Check your /etc/hosts file. You should have the localhost similar to the one below. Your ZCS server name should be replaced with the zimbra.test.com and zimbra fields. The IP address should be the IP address bound to the network interface [ip addr or ifconfig -a to confirm].
127.0.0.1 localhost.localdomain localhost 192.168.0.1 zimbra.test.com zimbra
If your ZCS server is behind a firewall or is being NAT'd. Make sure that resolution for the hostname on the ZCS server returns the internal IP information rather than the external IP. To test:
hostname -f zimbra.test.com
or
domainname -f zimbra.test.com
As long as one of the above returns the full hostname, use the command for the following. The MX lookups depend on how you are doing your mail domain and server hostname.
host `hostname -f` zimbra.test.com has address 192.168.0.1 host -t MX `domainname -f` zimbra.test.com mail is handled by 10 zimbra.test.com. host -t MX `domainname -d` test.com mail is handled by 10 zimbra.test.com.
You should also have reverse records (PTR) as well. Replace 192.168.0.1 using your internal ip address, it should return something like:
host 192.168.0.1 1.0.168.192.in-addr.arpa domain name pointer zimbra.test.com
Please review wiki page on split-DNS. This also shows the basics of actually setting up DNS/Bind on Linux:
http://wiki.zimbra.com/index.php?title=Split_DNS
The following is a more complete how-to for setting up DNS/Bind:
http://www.zimbrablog.com/blog/archives/2007/06/making-zimbra-bind-work-together.html/
lmtp_host_lookup
Also review the variable lmtp_host_lookup to see if it applies to your situation:
http://bugzilla.zimbra.com/show_bug.cgi?id=27988
su - zimbra postconf | grep host_lookup postconf -e lmtp_host_lookup=native postfix reload
smtp_host_lookup
Similar to above.
disable_dns_lookups
Similar to above.
Local DNS-BIND Configuration Example
The full blown example on setting up BIND is at Split_DNS article.
Detailed Example Zone Files
This example is from a CentOS5 test box I have behind a firewall. I actually setup a dynamic dns using a valid domainname, I've replaced my "real" domainname below with "example". I'm using DynDNS to do this.
Directory Structure
The default setup is a chroot configuration of BIND.
- The root of the configuration files is /var/named/chroot/ .
- The general bind configuration files are in /var/named/chroot/etc/
- Files you'll have there:
- db.cache
- localtime
- named.conf
- rndc.key
- Files you'll have there:
- The directory where your zone files will reside is /var/named/chroot/var/named/
- I have in this directory the following:
- data (a directory that's empty)
- slaves (a directory that's empty)
- internal.example.com.hosts (file for A, NS, MX, CNAME, etc. records)
- 0.168.192.rev (file for PTR records)
- I have in this directory the following:
/var/named/chroot/etc/named.conf example
Here's my named.conf file I'm using:
options {
directory "/etc";
pid-file "/var/run/named/named.pid";
};
zone "." {
type hint;
file "/etc/db.cache";
};
zone "internal.example.com" {
type master;
file "/var/named/internal.example.com.hosts";
};
zone "0.168.192.in-addr.arpa" {
type master;
file "/var/named/0.168.192.rev";
};
/var/named/chroot/var/named/internal.example.com.hosts
The _xmpp-server._tcp entries are related to jabber/xmpp and shouldn't be necessary for a default zimbra install. I'll leave them here just for a reference in case they are useful for others depending on the circumstances.
I had a second test box "mail4" at one point but I shut it down.
The one MX record with the starting blank space :
IN MX 10 mail3
would "assume" for the internal.example.com domain.
My only physical box is "mail3". The other names and domains are done so I can configure multiple domains on this box. The blank space MX record (for internal.example.com) is also setup on mail3. So, in total my mail3 box has zimbra configured to handle mail for these five domains:
- internal.example.com
- mail3.internal.example.com
- secondary.internal.example.com
- move.internal.example.com
- alias.internal.example.com
$ttl 38400
internal.example.com. IN SOA internal.example.com. ajcody.mail3.internal.example.com. (
1207910051
10800
3600
604800
38400 )
IN NS mail3
IN MX 10 mail3
mail3 IN MX 10 mail3
secondary IN MX 10 mail3
move IN MX 10 mail3
alias IN MX 10 mail3
mail4 IN MX 10 mail4
mail3 IN A 192.168.0.16
mail4 IN A 192.168.0.17
_xmpp-server._tcp SRV 5 0 5269 mail3
_xmpp-server._tcp.mail3 SRV 5 0 5269 mail3
_xmpp-server._tcp.secondary SRV 5 0 5269 mail3
_xmpp-client._tcp SRV 5 0 5269 mail3
_xmpp-client._tcp.mail3 SRV 5 0 5269 mail3
_xmpp-client._tcp.secondary SRV 5 0 5269 mail3
/var/named/chroot/var/named/0.168.192.rev
$ttl 38400
$ORIGIN 0.168.192.in-addr.arpa.
@ IN SOA mail3.internal.example.com. ajcody.mail3.internal.example.com. (
1207910558
10800
3600
604800
38400 )
IN NS mail3.internal.example.com.
16 IN PTR mail3.internal.example.com.
17 IN PTR mail4.internal.example.com.
Split-DNS - But I Already Have Bind Running Internally?
You should investigate using ACL's and the zone options for BIND to effective setup the "purpose" of split-dns situation without actually running it on a separate server.
Please see:
Other Variables That Are Effected By Lookups
zimbraInboundSmtpHostname New In 5.0.11
f your MX records point to a spam-relay or any other external non-Zimbra server, enter the name of that server in the Inbound SMTP host name field. This check compares the domain MX setting against the zimbraInboundSmtpHostname setting, if set. If this attribute is not set, the domain MX setting is checked against zimbraSmtpHostname.
