On Sep 13, 5:35 am, schaf <sc...@2wire.chwrote:
Hi NG!
I have a problem in my remote application.
After calling a remote function the calculation will be done by the
service. The calculation result will be sent to the caller (client)
via remote event.
The following behavior can be observed:
1.) Right after the start of the server the first response via remote
event will take a long time.
2.) Calling the same function a second time will not be a problem.
3.) If I enter the IP address of the client (caller) into the host
file, the first call will not take this long time.
So does .NET remoting use DNS reverse look-up to obtain the client
address?
If yes, is it possible to change this behavior or do I have to permit
DNS reverse look-up ?
I think you have it backwards. The IP address is the final resolution
level, not the computer name. When you pass it a computer name, the
system must do an address resolution, NOT a DNS reverse lookup. A DNS
reverse lookup is when you give it the IP address and want to get the
corresponding machine name(s). The reason it is "faster" when you
give it the IP address is because it DOESN'T have to go to the address
resolution; the IP address is already assumed to be resolved (that
doesn't mean it's not a BAD IP address, just that you have an IP
address). The results of a lookup are cached, or saved locally so
that the DNS service doesn't have to be called EVERY time you want an
address. That's why it doesn't take as long the second time around.
I don't remember the caching rules offhand, but I think the default
DNS cache TTL is actually set by the server after a query...
IP Addressing can be thought of like a telephone system (generally).
Each person (computer) has a particular phone number (IP Address) that
it can be contacted on. If you already have the phone number (IP
Address) you don't have to do anything, you just dial it. But if you
don't have the phone number (IP Address), you have to look it up in
the phone book (DNS Service). You find the name and now have the
number. There also exists a REVERSE phone book (reverse DNS lookup)
that allows you to find out the name of the person (computer) that is
at a particular phone number (IP Address). (for pedants out there,
YES I know this is simplified but is a fairly decent analogy for a non
ip guru <g>)