Web server in DMZ cannot access external DNS through ASA5510 Share on Facebook Post on reddit Tweet on Twitter Share on LinkedIn Home › Forums › Networking › Cisco Security – PIX/ASA/VPN › Web server in DMZ cannot access external DNS through ASA5510 This topic has 11 replies, 3 voices, and was last updated 11 years, 10 months ago by AndyJG247. Viewing 1 post (of 1 total) Author Posts tnshurtmMember Mar 10, 2009 at 9:33 am #139888 (ASA 5510) I have a web server that everyone can reach from externally, but I can not browse from it to the web unless I use IPs. DNS does not work. I have the DNS on the server pointing to my ISPs DNS servers. Is there a certain port I have to open on the outside or DMZ port to allow access to external DNS servers? Author Posts Viewing 1 post (of 1 total) You must be logged in to reply to this topic.