Unable to resolve host - VMware Technology Network VMTN

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Hi

I have a mail sever setup on my virtual machine.When i try to test the connection to the mailbox i get the following error:

"Error 16: Failed to connect to xxx.xxx.x.xx.

Could not resolve host"

Any idea why this is happening? 😐

12 Replies

1. Can you ping the IP address of this virtual machine (guest) from outside?

2. Is a firewall enabled in the guest?

3. Does it have a virtual NIC which is connected to a vSwitch which has a physical NIC assigned?

If you can ping it:

2. Which application throws this error? Which name resolution does it use? DNS or NetBIOS/WINS?

Check if the appropriate entries are made in DNS or if the NetBIOS/WINS setup is correct.

VCP / VMware vEXPERT 2009

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Hi

The virtual machine i am having the problem with is on a separate network from the one i am using.

The firewall is off.I am unable to ping since it is not on my network.

The appilcation i am using is a helpdesk software that send out email alerts.So i enter all the correct details but when i try testing the email service i get that error.

it has a 192.268.xx.x ip address which is static

Try to telnet port 25 of mailserver from your system.

Since it is an mailserver issue and diffrent network, please have SMTP port open on the VLAN settings. It may help you to communicate with mailserver.

Shan

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It might be better to test the ping and the telnet connection from the helpdesk system as if he can't ping the guest because it is on a different network (no router in between???) he might also not telnet it.

AWo

VCP / VMware vEXPERT 2009

vExpert 2009/10/11 [:o]===[o:] [: ]o=o[ :] = Save forests! rent firewood! =

I tried to telnet but it failed.

The firewall is off.sorry guys but im not that clued up on VM's so it will be a bit harder to fix for me.

We should check if the guest has a connection first.

Open the guest console, log on and try to ping its own IP address first. After that try to ping the default gateway which is configured for this host. Can you ping these addresses?

AWo

VCP / VMware vEXPERT 2009

vExpert 2009/10/11 [:o]===[o:] [: ]o=o[ :] = Save forests! rent firewood! =

As already mentioned, some ping tests to check connectivity.

1 - Check that the guest OS (the mail server) ping its own address?

2 - Check that the guest OS ping its network gateway?

(also complete this for the machine having issues connecting to the mail server)

Assuming these 2 are ok;

3 Check that the guest OS ping the machine you are initially using (the helpdesk server?) Maybe try to ping another machine on the same network

You mentioned that the Guest is on a separate network? check your netmask. you may be restricting traffic to only one network despite having the firewall open

check netmask on both machines i would expect you'd need 255.255.0.0 to work across multiple networks. if either are 255.255.255.0, that machine is restricted to a single IP range.

Your gateways also need the same netmask.

Hi Guys

I can ping the Machines IP and the gateway fine.

You see i have this helpdesk on this machine so everything runs of it.

Its a virtual Machine with an email server and the helpdesk software installed.

So basically it is all on 1 machine.This machine belongs to my develpment network that has all my vm's attached.

Still one thing you didn't try yet but that test was requested. Can the two servers which should communicate (Mail <-> Heldesk) ping each other by address? Not telnet, ping.

AWo

VCP / VMware vEXPERT 2009

vExpert 2009/10/11 [:o]===[o:] [: ]o=o[ :] = Save forests! rent firewood! =

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So 1 host and 2 guests but each guest is on a diferent subnet?

As already requested is there any ping communications between these machine. Also try a tracrroue on both machines so you get both sides of the path.

This should at lest locate where the problem is.

Hi Guys

I have sorted out the problem.It wasn't the VM that was causing the problem it was the email server.Aparently it need to point to its own IP address and SPA needs to be enabled.

Thanks for the effort