RE: [cobalt-users] Thanks re Qube2 relay problem assistance

["admin" <admin@xxxxxxxxxxxxx>]

So rebooting reloads the TCP/IP stack then.  Wish I could force it from the
ISP side.

Network Administrator		Email: admin@xxxxxxxxxxxxx
Beachlink				Phone: 252-261-0744 ext.202
3915 Welch St. P.O. Box 1528	Fax:   252-261-1365
Kitty Hawk, NC 27949

-----Original Message-----
From: cobalt-users-admin@xxxxxxxxxxxxxxx
[mailto:cobalt-users-admin@xxxxxxxxxxxxxxx]On Behalf Of Simon Billis
Sent: Monday, March 11, 2002 11:23 AM
To: cobalt-users@xxxxxxxxxxxxxxx
Subject: Re: [cobalt-users] Thanks re Qube2 relay problem assistance


I think that I may have the answer to the problem when you change IP
addresses or physical interfaces that are now responding with the same IP as
before.

The way that IP addresses are resolved to physical interfaces has something
to do with the problem.

When the domain is resolved to an IP address by the DNS server this answer
is sent to the host requesting the look up - in this case the pc.
The PC then tries to resolve the IP address to a MAC address using ARP.

In both instances, DNS and ARP, there are caches involved. The PC will cache
domain to IP address in a cache and then the IP to MAC address is cached in
the ARP cache. This improves performance on the PC however you will run into
problems when the IP address or the MAC address changes and the respective
entries in the caches have not yet timed out. To resolve this problem, get
the pc to reload the TCP/IP stack. This also affects Macs some 'nix boxes
and some routers, it depends on the TCP/IP stack implimentation.


Cheers

Simon


On Monday, March 11, 2002 2:57 pm, admin@xxxxxxxxxxxxx wrote:
>Just a quick note.  I've encountered this as well in my network.  It would
>always happen when I changed the ip address on my mail server.  Although
>clients only tell their pc's to look for my mail server by name; I'm
>convinced that the outlook programs (and have my suspicions about netscape
>and eudora) cache the damn ip address it resolves somewhere (perhaps the
>registry, I'm not sure yet).  I feel your pain though.
>
>-----Original Message-----
>From: cobalt-users-admin@xxxxxxxxxxxxxxx
>[mailto:cobalt-users-admin@xxxxxxxxxxxxxxx]On Behalf Of Malaika R.
>Ashanti
>Sent: Friday, March 08, 2002 6:07 PM
>To: cobalt-users@xxxxxxxxxxxxxxx
>Subject: [cobalt-users] Thanks re Qube2 relay problem
>assistance
>
>
>Thanks to all of you who provided assistance regarding the relay problem
>situation with my Qube2.
>
>I checked to make certain that everything that was mentioned was present
>and it was.
>
>Had the end-user recheck the OE configurations and all of the pop and
>smtp server information was entered correctly.  I asked him to reboot
>his system.  He was then able to send email.
>
>I have no idea what rebooting could have changed, but at least it is now
>working.
>
>Thanks again to all for such prompt and helpful responses.  At least I
>know more about the named.conf file, etc.
>
>Malaika


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