DNS Services with NATting?

[dvnguyen]

I currently have all my VMs connected to an internal network with NAT enabled so that they will have external access.  I am able to ping outside of my network using IP addresses but not using hostnames.  Therefore I cannot browse websites.  I've added my company's DNS server to both the VM's network configuration and in the organization's external network specifications.  I'm positive the DNS server works as it works outside of my vCD environment.  I'm not quite sure if it's because I have my network NATted or because of something else.  Any recommendations or ideas?

[peterdabr]

Hi,

Few basic steps to troubleshoot the issue in the following order: (sorry for the first two, but I can't tell whether it's been verfied based on the problem description):

-ping dns server from VM to confirm you have network connectivity

-confirm VM is set to talk to company's DNS  (Windows: run: nslookup ; Linux: cat /etc/resolv.conf)

-confirm org external network's firewall tab has 'allow any-any' rule for ougoing 'any' traffic (dns queries can be tcp or udp) (suh rule is always there by default unless removed manually)

-confirm DNS server can actually see incoming DNS queries from VM and that it can reply back (Linux: run: tcpdump ;Windows: wireshark, network monitor tool or similar)

-it would make sense to temporarily whitelist DNS server IP on org ext net firewall by specifying its IP for the source with destination being the natted ip of the vm

-lastly, you can enable logging on org ext net firewall to get more clues (though you should get the answer to the problem by running through previous steps

good luck 😉

Peter D.