client server performance drop when internet goes down

[Franky Leeuwerck_1]

Hello there,

We see a strange phenomen on one of our remote plant networks.

The W2000 clients (Chinese version), running OpenRoad4.1 applications, are defined on the same subnet as the Ingres 2.0 DBMS on HP-UX 11.

An external DNS is used.

Each time the internet line doesn't work, then performance of the client/server applications is dropping significantly.

This is very strange because the clients use the ip-address of the DBMS server in their middleware component (IngresNet) for establishing a DBMS connection, so there is no need for a DNS lookup, I guess.

What can cause this ?

Thanks in advance,
Franky

[John Bolene]

If the only DNS you use is external, the clients may be waiting for a DNS lookup of their own IP's.

You should have an internal DNS server for all internal IP's that also forwards requests to the external DNS for internet names and IP's.

[Jon Finley]

John's right... when you telnet to an HP box, it wants to qualify your address through DNS. You should notice that there is a timeout hang when logging on when access to DNS is down.

Jon

[Franky Leeuwerck_1]

Hello John & Jon,

Thanks for helping to solve this problem.
I am only aware of some basic DNS & networking stuff.

John,
The w2000 clients connect to the HP-UX DBMS server by using the servers ip-address.
Why should the clients be waiting for a DNS lookup of their own IP's in this case ?

Jon,
Similar question for your answer. Why should the DBMS bother to qualify the clients address if the clients connects with the ip-address ?

Regards,
Franky

[Mike Stevens_1]

Both Gents are correct. Windows 2000 relies on DNS highly when in a network setting. These clients are looking to the external DNS server to tell them where your HP-UX box is each time they are looking for it. I had a similar problem in a completely Windows 2000 network ( servers and clients ) where if the external DNS was unreachable ( internet was down ) network performance was slowed dramaticly. I would setup a DNS server on your HP-UX box or install a Windows 2000 Server and setup DNS on it. Then point all of your Windows 2000 PRO boxes to the newly installed DNS server and your network performance should come back up to speed and stay there regardless of your internet connection.

Hope this Helps,

Mike Stevens

[John Bolene · Accepted solution]

Franky

it has nothing to do with the application using an IP to connect to

it has everything to do with the terminal itself connecting to TCP/IP services on the server

[Franky Leeuwerck_1]

Mike,

Thanks for feedback.

[Franky Leeuwerck_1]

John,

Now, I realise that the problem is not the client being able to use the ip-address of the server to connect to it, but the fact that the simple addressing itself of the TCP/IP services of the server causes a DNS lookup on the server, I guess.

As you, and the other contributors suggest, a local DNS service will solve the problem, and that's what we are up to now.

Further I am anxious to know more about this process of clients addressing the TCP/IP services on the server. What is exactly happening causing a DNS lookup ? Is it possible to shortly point this out a bit more ?

Anyway, thanks for sharing your expertise.

Regards,
Franky Leeuwerck

[Jerome Henry]

Well,
Just because Windows has a long history of calling machines by names (the old Netbeui stuff), most of it's configuration goes thru names anyway, whereas it's your server of your client's name being to be resolved...

J

[Franky Leeuwerck_1]

Hello Jerome,

As mentioned earlier : the client uses an ip-address for connecting to the server.

If I understand what you explain then it is the server's name that is being resolved by the client. This way of doing things is typical for Windows TCP/IP networking, correct ?

Thanks for your input.

Regards,
Franky