DNS Records Configuration

A Records

Active Sync

For smooth functioning of Auto/SmartDiscover mechanism, it is necessary to configure A DNS record. There are two ways how to do it:

  • You can either set this record directly:

    autodiscover.<domain.com> - <IP_address>

    where IP_address is the address of the "main" server.

  • Or better you can set A record only for this "main" server + set a CNAME record (alias):

    autodiscover.<domain.com> - <server.domain.com>

    This way saves a lot of work in the case IP address of the "main" server is changed and you have set many aliases instead of many A records.

SRV Records

WebDAV

For Apple CalDAV/CardDAV clients you need to configure DNS records otherwise they will not be able to connect. Also if the hostname is different to the domain name, then a DNS SRV record should be configured to point to the actual hostname.

Note: If the hostname is different to the domain, then a DNS SRV record should be set up by the domain owner.

The syntax of SRV records for standard HTTP (port 80) and HTTPS (port 443) access:

_caldav._tcp.<Domain>. 86400 IN 0 5 80 <Host>

_caldavs._tcp.<Domain>. 86400 IN 0 5 443 <Host>

Where Domain is the domain to be contacted and Host is the actual host, so if you are the owner of domain icewarpdemo.com and you are running your IM server as im.icewarpdemo.com you should create a DNS SRV record as follows:

_caldav._tcp.icewarpdemo.com. 86400 IN SRV 0 5 80 im.icewarpdemo.com

Note: This full record form is to be used when you want to edit a zone file directly. When using any interface, just fill in the appropriate fields.

The same applies for CardDAV:

_carddav._tcp.<Domain>. 86400 IN 0 5 80 <Host>

_carddavs._tcp.<Domain>. 86400 IN 0 5 443 <Host>

i.e.:

_carddav._tcp.icewarpdemo.com. 86400 IN SRV 0 5 80 im.icewarpdemo.com

Warning: These records are necessary for Apple clients (iCal and Address Book in Mac OS X 10.6 and later). Without these records, the client applications will be unable to find location of the WebDAV service. (Searching algorithm prefers this SRV record information, if available. If not, the client tries to connect to the specified server using the following ports: 8800 (CardDAV), 8843 (CardDAV + SSL), 8008 (CalDav) or 8443 (CalDAV+SSL)).

It is probable that other clients will follow this trend.

SIP

Syntax for SIP is as follows:

_sip._tcp.<domain.com>

_sip._udp.<domain.com>

_sip._tls.<domain.com>

Other parts are same.

XMPP

Syntax for XMPP is as follows:

_xmpp-server._tcp.<domain.com>

_xmpp-client._tcp.<domain.com>

Other parts are same.