Strange RAS/VPN Behavior

  • Thread starter Thread starter bayers
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bayers

I've set up a rras server at work with pretty much the default settings
except for adding the DHCP routing info.

I home I have an XP pro client connected via broadband. It has a VPN
connection with the default settings too.

The client connects to the server just fine.

For the first few seconds, everything works, then, all of a sudden, I
can't resolve names on the work network.

Using tracert, I've discovered that, at first, there is one hop to the
server as you'd expect when you're on the same network, but after a few
seconds, it starts trying to go out on the internet to find the server
and doesn't use the VPN connection.

The DC that the rras server is on does a lot of things. DHCP, dynamic
DNS, Directory services, web server and so on. We're a small outfit.

I noticed that when I use ipconfig /all, it shows that the dns servers
for the ppp connection are the dns servers configured for the network
card on the server and not those for the DHCP server. (I can tell
because the secondary servers have a different ip)

ipconfig /renew times out, but that might be how vpn connections
behave. I don't know.

Sometimes if I do a ipconfig /dnsflush on the client, things will return
to normal again but not always. It seems very inconsistant and things
are not repeatable.

The only thing unusual about the hardware setup that I can think of is
that the server has two network cards that load share in tandom. Intel
1000/MX server, I think.

There also might be another DHCP server on the network somewhere. It
would be another department's.

I've posted once before, but none of those solutions worked. Thanks for
the suggestions though. I'm stuck.
 
There are plenty of thing to go wrong in a setup like this.

First up, this is why the DNS server value changes. When a client
connects, this address is set to the address configured on the RRAS server.
This is part of the PPTP negotiation to set up the connection. DHCP is not
involved (and cannot be accessed at this stage). Once a connection is made,
the client can send a DHCPINFORM message to the DHCP server to get the
options set there.

Doing an ipconfig/renew while connected isn't a great idea. The remote
client doesn't get its IP from DHCP. It gets it directly from the RRAS
server as described above. If you look at your DHCP leases, you will see a
batch of addresses leased to the RRAS server for this purpose.

If you have problems, disable all the auto stuff for DNS and set the DNS
server IP and the DNS suffix(es) manually in the client's connection
properties (Advanced TCP/IP settings) to match the LAN clients. Then it will
use these when connected.

Having a remote access server running on your first/only DC can also
cause problems with DNS if you have dynamic DNS running. See KB 289735.
 
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