DNS/DHCP Server on same platform as 3CX Server

[petewatterschats]

The documentation says not to install a DNS/DHCP server on the same windows platform as the 3CX server. Why? What is the Danger? I have a DNS/DHCP server installed on the same windows platform as the 3CX Server and have seen no negative results.

 

[leejor]

The same platform as in " the same operating system", or the same platform as in "the same machine"? That would need to be clarified.

 

[bob222]

I think he means on the same physical or virtual server that 3CX is running on.

I have the same question regarding the restriction of running a DHCP server service on the same server running 3CX. That restriction was added with version 14 of 3CX. From the documentation of various versions, there is a progression of restrictions:

Version 11
No restrictions

Version 12
3CX Phone System should not be installed on a host which features DNS or MS SharePoint services

Version 12.5
3CX Phone System must not be installed on a host which features DNS, MS SharePoint or Exchange services.

Version 14
3CX Phone System must not be installed on a host which is a DNS or DHCP server, has MS SharePoint or Exchange services installed.

I understand the restrictions on SharePoint and Exchange -- those can be very demanding on server resources, and tend to require use of ports 80 and 443.

For DNS, I found this post http://www.3cx.com/blog/docs/free-edition/ which states:

"Firstly make sure that your are not installing 3CX Phone System on a machine that has:

•DNS – A DNS Server takes all available ports on the local host and may result in no available ports for Audio for example."

I had not heard of DNS taking all available ports, so I checked into that. I found this article:
http://www.foxguardsolutions.com/resources/details/a-closer-look-at-windows-dns-ports

That article indicates that 2500 ports are opened by the DNS server. That's not all available ports, but it is a good size chunk. Maybe that could cause a problem with 3CX.

For DHCP, if the server and phones are on a separate VLAN (which, in my case, they are) it sure is convenient to have the server on which 3CX is running to also provide the DHCP service for all of the phones. I can't imagine that for even a couple of hundred phones that this would add any significant load to the server, or otherwise interfere with 3CX. So, I really don't understand why that restriction was added for version 14 of 3CX.

 

[leejor]

So, I really don't understand why that restriction was added for version 14 of 3CX.

Perhaps they came across an issue that arises on occasion, with certain combinations of hardware/phones/gateways, etc. While you may have success 99.9% of the time, someone else may not. It is probably wiser to say, "this must not be installed...., than to say "it should work most of the time, but you may have some problems". You don't want even a small number of customers complaining that their system is failing at times, and the find that it was a known issue.

 

[ian.watts]

The issues, while technical in nature, are more from a support perspective. Yes, the ports used by 3CX and other services and be properly trained up to coexist.. but out of the box they are not. Supporting such an environment introduces trying to referee colliding ports used by different services. As a 3CX support agent, I wouldn't want to start digging into why DNS is occupying ports you need 3CX to listen on. Even though technically it is a trivial matter, digging into those inner workings on somebody else's system is not something you want to end up liable for "blowing up" other things.

Makes good sense to me as to "why" it isn't supported. It can be done by a good sysadmin.
Then again, given the platform runs even on Windows 10 and as a VM.. why not just dedicate something to it and throw away all those potential problems?..

 

[petewatterschats]

Mine s same PC windows 8.1 which hosts 3CX and DNS/DHCP Server

The DNS/DHCP server I am running is from a 3rd party not Microsoft