After installing ASA 5505 at our client's site, they are not able to browse their internal server using url now. But they can access it using servername and ip address. I've already enabled port 53 to outside port as the DNS server is outside the network.
When you say they can access it with ip, do you mean the internal ip?
The problem most likely is that the url is resolving to the public ip address which is not reachable from inside the ASA.
You have a few options to fix this. One is to edit the clients hosts file so the url resolves to the inside ip. Second is to use dns doctoring on the ASA to change the response from the dns server from public ip to private. Third is using hairpinning on the inside interface of the ASA.
There is a note in DNS doctoring that "DNS rewrite is not compatible with static Port Address Translation (PAT) because multiple PAT rules are applicable for each A-record, and the PAT rule to use is ambiguous."
If I'm using PAT, should you recommend hairpinning instead of DNS doctoring?
Table of ContentsIntroductionVersion HistoryPossible Future
UpdatesDocuments PurposeNAT Operation in ASA 8.3+ SectionsRule Types
Network Object NATTwice NAT / Manual NATRule Types used per SectionNAT
Types used with Twice NAT / Manual NAT and Network Obje...
Table of Contents Introduction:This document describes details on how
NAT-T works. Background: ESP encrypts all critical information,
encapsulating the entire inner TCP/UDP datagram within an ESP header.
ESP is an IP protocol in the same sense that TCP an...