Does ASA support FQDN?

Does ASA support FQDN?

Introduction. Introduced within Cisco ASA version 8.4(2), Cisco added the ability to allow traffic based on the FQDN (i.e domain name). This feature works by the ASA resolving the IP of the FQDN via DNS which it then stores within its cache. Traffic is then either denied or permitted accordingly.

How do I enable FQDN in Asa?

Basic Configuration

1. Step 1: Define DNS server. Since the ASA has to be able to resolve each hostname to one or more IP addesses, we must define what DNS server the ASA can use.
2. Step 2: Create the FQDN object for the host name in question.
3. Step 3: Add the FQDN Oject to an ACL.

What is FQDN in Cisco?

Complete Definition. A fully qualified domain name (or FQDN) is an unambiguous domain name that specifies the exact location in the Domain Name System’s tree hierarchy through to a top-level domain and finally to the root domain. Technically, a FQDN has a trailing dot. For example: somehost.example.com.

How configure DNS Cisco ASA?

Procedure

1. On the Devices & Services page, select all the ASAs on which you want to configure DNS.
2. Click Command Line Interface .
3. Click the CLI macro favorites star .
4. Click the Configure DNS macro in the Macros panel.
5. Click >_View Parameters and in the parameters column, fill in the values for these parameters:

Which port is DNS?

UDP Port 53
The answer is DNS is mostly UDP Port 53, but as time progresses, DNS will rely on TCP Port 53 more heavily.

How do I enable DNS lookup in ASA interface?

How to Enable DNS Lookups on Cisco ASA5500

1. Connect to the ASA, log in and go to enable mode, and then global configuration mode.
2. Now if you have corporate DNS server on your LAN you might prefer to use those, so you would use ‘inside’ as opposed to ‘outside’.

What is FQDN in networking?

A fully qualified domain name is the full length DNS name associated with a resource on the IP network (eg the Internet) and representing a branch in the DNS hierarchy (eg [www]. As an extension, FQDN could be used for any kind of DNS records, not only IP names, for example TXT records can be associated to FQDN.

What is ACL FQDN?

The Configuring an FQDN ACL feature allows you to configure and apply an ACL to a wireless session based on the domain name system (DNS). The domain names are resolved to IP addresses, the IP addresses are given to the client as part of the DNS response, and the FQDN is then mapped to an ACL based on the IP address.

How do I find my DNS ASA?

Provided the DNS servers are contactable, you can issue the ping command with a website url and you will see the resolution. It is possible to gain further insight with the debug dns resolver command. The ASDM configuration window resides at Configuration > Device Management > DNS > DNS Client.

Why is port 53 blocked?

Zone transfers take place over TCP port 53 and in order to prevent our DNS servers from divulging critical information to attackers, TCP port 53 is typically blocked.

What happens if the ASA is unable to resolve the FQDN?

Should this occur, and the ASA is unable to resolve the IP of the FQDN then the ACL will be marked as ‘inactive’, as shown below. Though not a direct caveat, the way in which the use of the ‘expiry timeout value’ is good to know.

How long does it take for Cisco ASA to re-query DNS?

The DNS server returns an IP of 1.1.1.1 with a TTL of 5 minutes. The ASA then adds this entry to its cache with a TTL of 7 minutes. After the 5 minutes (the original TTL) has expired the ASA re-queries DNS*.

Is the FQDN ACL a replacement for URL filtering?

It should be emphasized that this new FQDN ACL feature on the ASA is not a replacement for URL filtering solutions. Administrators attempting to write basic ACL policies that permit or deny traffic to FQDN names outside of their organization might have intermittent success, due to the factors discussed below.

When does the ASA resolve the Ace hostname?

When the ASA receives the response from the DNS server for the ACE hostname resolution, the answer has a Time to Live (TTL) associated with it. The ASA will keep that domain-to-ip mapping active until the TTL expires, at which time the ASA will re-resolve the IP address of the hostname.