Troubleshooting DTCPing Errors

So I am running DTC ping between 2 machines on our network and am getting the following error

++++++++++++++++++++++++++++++++++++++++++++++
     DTCping 1.9 Report for WEB2  
++++++++++++++++++++++++++++++++++++++++++++++
RPC server is ready
++++++++++++Validating Remote Computer Name++++++++++++
03-03, 13:39:45.099-->Start DTC connection test
Name Resolution:
    internal-->10.20.3.236-->internal.something
03-03, 13:39:45.114-->Start RPC test (WEB2-->internal)
Problem:fail to invoke remote RPC method
Error(0x6BA) at dtcping.cpp @303
-->RPC pinging exception
-->1722(The RPC server is unavailable.)
RPC test failed

I have also run RPC ping where I get what I beleive is the same error:

C:\Program Files\Windows Resource Kits\Tools>rpcping -s internal

Exception 1722 (0x000006BA)
Number of records is: 4
ProcessID is 5876
System Time is: 3/3/2011 2:44:12:822
Generating component is 8
Status is 1722
Detection location is 323
Flags is 0
NumberOfParameters is 0
ProcessID is 5876
System Time is: 3/3/2011 2:44:12:822
Generating component is 8
Status is 1237
Detection location is 313
Flags is 0
NumberOfParameters is 0
ProcessID is 5876
System Time is: 3/3/2011 2:44:12:822
Generating component is 8
Status is 10060
Detection location is 311
Flags is 0
NumberOfParameters is 3
Long val: 135
Pointer val: 0
Pointer val: 0
ProcessID is 5876
System Time is: 3/3/2011 2:44:12:822
Generating component is 8
Status is 10060
Detection location is 318
Flags is 0
NumberOfParameters is 0

I'm pretty sure that the exception number 1722 is the key but I can't find any info about it.

There may be a firewall with ports that need opening between the machines which I am checking with our sys admins now. But I can do a regular ping between the machines.

Other than that I am reading a lot of articles talking about OS services and components I know nothing about and am having trouble finding any info on. Can anyone shed any light on this?

FYI the machine is running Windows Server 2003 RS SP2.

RPC uses random high ports, which are in all likelihood being blocked by any firewall that happens to be between the devices.

It's possible to lock it down to a set range of ports so that this range can be allowed through the firewall; this KB article covers the process.

In my last unpleasant DTC-through-a-firewall experience, aside from needing to hardcode the port range, I recall needing to make some other arcane reg hacks, as well as relax a number of the security settings in the Component Services Management tool against my better judgement. Hopefully you have better luck; start with the ports and see how it goes!

(P.S., why the heck do applications still use and microsoft still support DTC?)