unable to reach exchange when internet down

[tekkanet]

Hello,
I have an exchange 2003 connected to an internal lan and to the internet.
My lan clients have outlook 2003 (no cache profile).
Suppose I have an outlook client connected and opened.
Internet goes down (many thanks mamma telecom!).
The outlook already connected continues to be able to read current received mails and folders of its mailbox and to send to internal exchange adresses.
Instead, if a new outlook client pc tries to open, it receives (after minutes.......) the message "unable to reach exchange server".
The same if the already connected client closes outlook and then re-tries to open it....
Also, going through mail configuration and trying to reconfigure the exchange server, giving the internal ip address gives the same fault.
Is it a misconfiguration of mine or do I have to thanks Bill?

clients are winxp with static ip address and if I do a "ping mailserver" I can do it successfully (internal ip of mailserver returned...)

i would like to have clients at least access their mailbox if internet goes down...

thanks in advance for your help.

Gianluca

 

[markdmac]

Sounds to me like your DNS is not configured properly.

DNS Settings:

Configure the server NIC to only list itself or other DCs, no ISP DNS gets configured on the NIC TCP/IP properties.

In DHCP, set the DNS scope option to only provide the IP of your local DNS server

For any statically configured IPs, make sure the DNS only lists local DNS servers and not ISP DNS.

In the DNS snap-in on the forwarders tab enter your ISP DNS.

I hope you find this post helpful.

Regards,

Mark

Check out my scripting solutions at

http://www.thespidersparlor.com/vbscript

 

[firthm]

Hi tekkanet,

On your Exchange box, what is the output from ipconfig /all?

Thanks,
Mike

Michael Firth
Network Infrastructure Officer

~If it's not broke, break it and LEARN~

 

[tekkanet]

Mark, what do you mean with "Configure the server NIC to only list itself or other DC"? And does it refer to both internal and external nic?
mike, ipconfig /all gives
Windows IP Configuration

Host Name . . . . . . . . . . . . : MAILSERVER
Primary Dns Suffix . . . . . . . : pevianimail.local
Node Type . . . . . . . . . . . . : Unknown
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No
DNS Suffix Search List. . . . . . : pevianimail.local

Ethernet adapter LAN:

Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Intel(R) PRO/1000 MT Server Adapter
Physical Address. . . . . . . . . : 00-0E-0C-2E-74-40
DHCP Enabled. . . . . . . . . . . : No
IP Address. . . . . . . . . . . . : 192.168.0.7
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . :
DNS Servers . . . . . . . . . . . : 192.168.0.7
151.99.125.2
151.99.125.3
151.99.250.2

Ethernet adapter Internet Connection:

Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Intel(R) PRO/1000 MT Network Connection
Physical Address. . . . . . . . . : 00-C0-9F-36-81-B4
DHCP Enabled. . . . . . . . . . . : No
IP Address. . . . . . . . . . . . : my public ip addr
Subnet Mask . . . . . . . . . . . : 255.255.255.248
Default Gateway . . . . . . . . . : router public ip addr
DNS Servers . . . . . . . . . . . : 192.168.0.7
151.99.125.2
151.99.125.3
151.99.250.2

 

[firthm]

Hi Tekkanet,

It looks as though (depending on your network) as though you may just need to add a static route to the server?

Have your tried adding a route saying that any traffic from the servers local subnet should be routed via your internal DFG?

I.e.:
route add 192.168.0.0 mask 255.255.255.0 rtr_addr metric 1 -p

I think your server may be looking to the internet router to reply to your clients, a static route should tell it the correct direction to route in.

I hope this helps...

Mike

Michael Firth
Network Infrastructure Officer

~If it's not broke, break it and LEARN~

 

[markdmac]

DNS Servers . . . . . . . . . . . : 192.168.0.7
151.99.125.2
151.99.125.3
151.99.250.2

This is what I was talking about. You have ISP DNS servers listed on your server's NIC. Remove them. You want to add those ISP DNS servers to the Forwarders tab in DNS.

I hope you find this post helpful.

Regards,

Mark

Check out my scripting solutions at

http://www.thespidersparlor.com/vbscript

 

[tekkanet]

Mike,
according to the route table it seems that the routing towards 192.168.0.0 network is by default ok....
C:\Documents and Settings\Administrator>netstat -rn

IPv4 Route Table
===========================================================================
Interface List
0x1 ........................... MS TCP Loopback interface
0x10004 ...00 0e 0c 2e 74 40 ...... Intel(R) PRO/1000 MT Server Adapter
0x20003 ...00 c0 9f 36 81 b4 ...... Intel(R) PRO/1000 MT Network Connection
===========================================================================
===========================================================================
Active Routes:
Network Dest Netmask Gateway Interface Metric
0.0.0.0 0.0.0.0 router_ip 85.32.44.139 10
[snip] internet routes
127.0.0.0 255.0.0.0 127.0.0.1 127.0.0.1 1
192.168.0.0 255.255.255.0 192.168.0.7 192.168.0.7 10
192.168.0.7 255.255.255.255 127.0.0.1 127.0.0.1 10
192.168.0.255 255.255.255.255 192.168.0.7 192.168.0.7 10
255.255.255.255 255.255.255.255 router_ip intern.ip 1
255.255.255.255 255.255.255.255 192.168.0.7 92.168.0.7 1
[snip] other routes
Default Gateway: 85.32.44.137

Mark, I read in exch. documentation about setting as primary dns the internet ip itself of the exchange server and then to set as secondary an tertiary the public dns of the provider...
So it seems is not the correct way...
Are you referring to dsnmgmt application?
In it, under "forward lookup zones" I have two folders:
_msdcs.pevianimail.local
and
pevianimail.local

where do I have to set, or where can I find correct docs?
the server was setup long time ago by other guys who left no docs about it....
thanks,
Gianluca

 

[markdmac]

On each server: In network connections, right click the local NIC and choose properties. In the DNS server list remove the ISP DNS. Click OK.

On the DNS server(s): Go into the DNS snap in found under Adminstrative Tools. Right click the server name and choose forwarders. Add the ISP DNS there.

I hope you find this post helpful.

Regards,

Mark

Check out my scripting solutions at

http://www.thespidersparlor.com/vbscript

 

[teqmod]

Here is an article on configuring DNS. I agree this is most likely your problem. The article is for server 2003 but can be used for earlier versions as well.

http://support.microsoft.com/kb/323380

 

[Zelandakh]

Or follow Mark's details which will fix the problem.

 

[xwire]

Hey folks, I am having a similar problem. When a user fires up Outlook there is a 30-60 second delay. Its definetly going outside of our network and trying to hit the Exchange server from the outside as I see the Deny message on our Firewall. I followed Mark's advice but I dont have any ISP DNS's listed there, but I did check and had no forwarders to the ISP DNS's listed so I added those. Would you folks think that would solve the problem? What is happening in the users outlook profile is that it is resolving to the wrong address, what I mean is that the server listed there is Exchange.abc123.com instead of Exchange.abc123.local. I also looked at the name servers in the DNS and there is one listed for the Exchange.abc123.com and it points to the external IP, I dont recall why its in there, but any help would be appreciated. I had also changed the firewall software around the same this started happening so I was suspicious of the firewall causing this, but can see where.

 

[markdmac]

xwire, your problems are a bit different. Please start a new thread.

I hope you find this post helpful.

Regards,

Mark

Check out my scripting solutions at

http://www.thespidersparlor.com/vbscript

 

[xwire]

I thought so, thanks