Why does it take an application using TCPIP, so long to start?

TCPIP 1 Minute

I had problems with a couple of applications taking over 30 seconds to start. For example FTP and the RMF DDS Server.


I found this was cause by my TCPIP resolver was misconfigured. An application can ask DNS for the IP address(10.1.1.2) or the string address (BBC.CO.UK) from the TCPIP Resolver function. On my system this was configured in ADCD.Z31A.TCPPARMS(GBLTDATA) as

LOOKUP DNS LOCAL

This says, go to the network, and ask the DNS server “out there” for information. If this request times out, use the local information. On my system the path to the DNS server was not configured, so it waited, and eventually timed out.

When I changed the LOOKUP definition to

LOOKUP LOCAL

it came up with no delays.

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Published by Colin Paice

I retired from IBM where I worked on MQ on z/OS, and did customer stuff. I retired, and keep my hand in with MQ, by playing with it! I'm now an #IBMChampion from my work trying to make z/OS product more usable.

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