iMac not connecting to 1 particular IP

[ndraves]

I'm having a bit of a problem with an iMac as follows:

It has full internet connectivity and there's no problems anywhere apart from when I try to connect to a particular exchange email server using the servers url or public IP.

The server is on the same network as the iMac and if I try to connect to the OWA by entering the private IP, 192.168.x.x, then it connects fine. If I try to connect to the URL, https://mycompany.co.uk/owa, then nothing, it just times out.

It is getting the correct DNS reply for the public IP, 188.x.x.x, and if I substitute this in the address bar then still nothing.

All the other computers on the network (Mac + Linux + Win + iPhone) work fine with email clients and with the web access OWA. Also access from the internet (other office/home etc) works fine too.

It's just this one iMac and I have no ideas why only the public address will not connect?

Finally when I try all this having unplugged the ethernet cable and run it with Wifi then it works. I also doesn't matter what IP address the ethernet port is on, doesn't work on any.

Any ideas?

 

[talmy]

It sounds like you aren't using your local DNS server but are instead connecting to an external one. DHCP should be providing you with a DNS server on your LAN which will respond with the 192.168.x.x address for mycompany.co.uk rather than the external 188.x.x.x address. I would expect that using the external address causes you to get blocked by your company's firewall.

You can check this by going to System Preferences, Network, and clicking on Advanced. The DNS pane should show the server being used.

 

[TechnoDestructo]

It doesnt connect because the site doesnt exist.

Server not found
Firefox can't find the server at mycompany.co.uk.

 

[GGJstudios]

It doesnt connect because the site doesnt exist.

Server not found
Firefox can't find the server at mycompany.co.uk.

False. The site does exist:

Domain name:
mycompany.co.uk

Registrant:
Easynet Ltd

Registrant type:
UK Limited Company, (Company number: 2954343)

Registrant's address:
Thomas More Square 5
Chancellor House
London
E1W 1YW
United Kingdom

Registrar:
Easynet GmbH [Tag = EASYNET-DE]
URL: http://www.autodomainsystem.com

Relevant dates:
Registered on: 08-Jul-1997
Renewal date: 08-Jul-2011
Last updated: 25-Nov-2010

Registration status:
Registered until renewal date.

Name servers:
ns0.easynet.co.uk 195.40.1.250
ns1.easynet.co.uk 195.40.0.250

WHOIS lookup made at 04:01:40 20-May-2011

 

[ndraves]

Sorry I should have been clear, mycompany.co.uk isn't my address. I was just using it as something like .....co.uk.

I suppose I was just being too security concious but I wasn't going to give out the actual URL. (I know its public anyway).

The actual domain is exchange.dbyj.co.uk

 

[ndraves]

It sounds like you aren't using your local DNS server but are instead connecting to an external one. DHCP should be providing you with a DNS server on your LAN which will respond with the 192.168.x.x address for mycompany.co.uk rather than the external 188.x.x.x address.

I don't think this is a DNS issue because as I said if I manually enter the IP (no DNSing) it still doesn't work. I have tried both internal and external DNS on this machine and no difference.

Also the fact that it works with the WLAN adapter suggests that the DNS is fine.

I would expect that using the external address causes you to get blocked by your company's firewall.

The firewall is correctly configured for internal/external use. All other machines work to access the Exchange from internal and external suggesting that the relevant ports are open.

 

[wpotere]

Besides DNS has nothing to do with it as he actually tried using just the IP.

What happens if you ping that IP from that Mac? Do you get a response? If not, we are looking at a routing issue. If you do, then it "might" be a firewall issue. If you are on an internal network, you might try turning the Mac firewal off to see if the site comes up.

 

[ndraves]

What happens if you ping that IP from that Mac? Do you get a response? If not, we are looking at a routing issue. If you do, then it "might" be a firewall issue. If you are on an internal network, you might try turning the Mac firewal off to see if the site comes up.

It pings fine. As I mentioned it's just this iMac so when I get to that computer I'll see if the firewall on the iMac has anything to do with it. Cheers

 

[talmy]

The server is on the same network as the iMac and if I try to connect to the OWA by entering the private IP, 192.168.x.x, then it connects fine. If I try to connect to the URL, https://mycompany.co.uk/owa, then nothing, it just times out.

It is getting the correct DNS reply for the public IP, 188.x.x.x, and if I substitute this in the address bar then still nothing.

I was thinking "DNS" because 192.168.x.x worked, 188.x.x.x didn't, and the DNS reply was 188.x.x.x when it should be 192.168.x.x. The local DNS server should be replying the LAN address, but if he is connecting to an external server instead he wouldn't, of course, get the LAN address.

That 192.168.x.x worked and 188.x.x.x didn't implies that the firewall is blocking access from the public IP address, which is fine but in this case is part of the problem.

 

[ndraves]

That 192.168.x.x worked and 188.x.x.x didn't implies that the firewall is blocking access from the public IP address, which is fine but in this case is part of the problem.

All the other computers on the internal network can access both the internal and external address of the server. Also other computers outside my network have no problem accessing the server.

Scratching my head on this one??

 

[wpotere]

All the other computers on the internal network can access both the internal and external address of the server. Also other computers outside my network have no problem accessing the server.

Scratching my head on this one??

Last bit that I would try is totally deleting the adapter and re-add it. It could be nothing more than a corrupt file or something. If all of the settings are correct and that computer can access other sites and nodes on the network then I am stumped. This box isn't on a different VLan is it?

 

[TechnoDestructo]

Correct. The site doesn't exist, its only registered:

I fixed your false statement.