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Re: DNS Search Rules



fixed

It not a PING thing. It is how the OS/TCP handles resolving a name to an
address.

We did finally change the the parm from *DFT to the long domain to fix it.

There appears to be lots of RFC's for DNS. I am hoping someone can point me
to an RFC or other Standards type doc that spells out how DNS is to search
for a IP address when given just a short name not a FQN



On Thu, Jul 17, 2014 at 6:50 AM, CRPence <CRPbottle@xxxxxxxxx> wrote:

On 16-Jul-2014 18:56 -0500, Kirk Goins wrote:

How the iSeries at 7.1 does it.
CFGTCP Option #12
Host Name = HHHHH
Domain name = xxxxx.yyyyyy.com
Domain search list = *DFT

Do ping to some name like just plain old BOB
The iSeries searches for BOB.XXXXX.YYYYYY.COM
If not found the iSeries searches for BOB.YYYYYY.COM
Per my client that 2nd search should not happen
Per IBM that is compliant with DNS standards
In this case it was causing issues and invalid address was being
returned.

Da question for any DNS GURU's Can you point me to and RFC or ??

That outlines the correct search method that a computer should do
per standards. I want to provide docs that prove that he DNS search
function on the iSeries is working or not working correctly.


Just a WAG:

I expect the question could be more about the PING utility\feature, than
about the DNS [search].?

Just as the Verify TCP/IP Connection (VFYTCPCNN) [aka PING], according
to the docs\help-text, "appends the local domain to a host name if a domain
is not specified ...", something that appears to match standard effects of
DNS search, there is nothing stopping that utility from attempting to
repeat that work by having appended the similar but larger domain.? That
is, there is nothing obvious to imply that the PING utility, after
determining that the host name with the local domain could not be resolved
to an IP address, could not [instead of immediately failing with msg
TCP3202] try to resolve the host name again, but having appended a
different domain; such that if the DNS successfully resolves that alternate
name to an IP address, then the utility could proceed by providing results
for the host with that other domain qualifier.? That would be from two
distinct gethostbyname() API requests rather than just one; the effects
would not be a result of one request for which the DNS search list [order]
played a direct role.

Perhaps eliminate the PING completely, and test just the effect of using
the DNS with the gethostbyname() sockets API.

Note: if the local host table has an entry for BOB [perhaps also if an
entry exists for?: BOB.XXXXX.YYYYYY.COM], then AFaIK the described effect
would be a valid\legitimate reason for the effects of gethostbyname() to
succeed, but having returned the IP address from [the local entry in] that
table.

--
Regards, Chuck
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