DDNS server-side solution

Carlos Cantu/Boulder/IBM ccantu at us.ibm.com
Thu Aug 24 16:19:57 UTC 2000



Using a proprietary DHCP client, I ask the DHCP server (using the FQDN
option) to do DNS Updates on the client's behalf.
The client asks for 'myname.can2dom.com'.
The server has been configured to give a permanent address with the
hostname 'servname' and the same domain.
As you may have guessed by my names, this is just a local test evironment.
And my DNS server and DHCP server are the same machine.

The server wins the battle of names because I can't ping using 'myname',
but I can using 'servname.can2dom.com'.  We might conclude that DHCP worked
since the client has an IP and the Dynamic Update worked because I can ping
by name immediately following the client's boot.

However nslookup gives some creepy answers.  Here's some of my output
below.  I'm hoping it's just a simple thing like the DHCP server added an A
record but not a PTR record because I can seem to do name-to-IP resolution,
but not IP-to-name.  I've also read that ping uses Winsuck (oops I mean
Winsock) and nslookup uses DNS queries and that might create some
differences in output.

D:\>ping myname.can2dom.com
Unknown host myname.can2dom.com.

D:\>ping servname.can2dom.com

Pinging servname.can2dom.com [9.99.165.204] with 32 bytes of data:

Reply from 9.99.165.204: bytes=32 time<10ms TTL=64
Reply from 9.99.165.204: bytes=32 time<10ms TTL=64
Reply from 9.99.165.204: bytes=32 time<10ms TTL=64
Reply from 9.99.165.204: bytes=32 time<10ms TTL=64

Ping statistics for 9.99.165.204:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 0ms, Maximum =  0ms, Average =  0ms

D:\>tracert servname.can2dom.com

Tracing route to servname.can2dom.com [9.99.165.204]
over a maximum of 30 hops:

  1   <10 ms   <10 ms   <10 ms  9.99.165.204

Trace complete.

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!  9.99.165.99 is my DNS server          !!!
!!!  9.99.11.39 is the 'real' DNS server   !!!
!!!    on a different domain               !!!
!!!                                        !!!
!!!  I can't get any IP addresses to play  !!!
!!!  with without registering first with   !!!
!!!  pscnames.  So he thinks IP 204 is     !!!
!!!  carlos.penn...  Since I'm just trying !!!
!!!  to test DDNS, I am disjoint and as-   !!!
!!!  sign a different name to the same IP  !!!
!!!  address.  Not nice I know but I       !!!
!!!  should be able to do nslookup on this !!!
!!!  IP address right?                     !!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
D:\>nslookup 9.99.165.204
*** Can't find server name for address 9.99.165.99: Non-existent domain
Server:  pscnames.penn.boulder.ibm.com
Address:  9.99.11.39

Name:    carlos.penn.boulder.ibm.com
Address:  9.99.165.204


D:\>nslookup 9.99.165.204
*** Can't find server name for address 9.99.165.99: Non-existent domain
*** Default servers are not available
Server:  UnKnown
Address:  9.99.165.99

*** UnKnown can't find 9.99.165.204: Non-existent domain


If anyone has any ideas as to whether the dynamic update did it's job or
not, I'd appreciate it.

Thanks

Carlos




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