Infraestructura eléctrica y electrónica

The table below provides an overview of the steps required to make the Barracuda Firewall an authoritative DNS host.

Task Explanation

1. Enable Authoritative DNS on the Barracuda Firewall

Enable the DNS Server service on the links and the service on the Barracuda Firewall.

2. Create One or More Domains Define one or more domains on the Barracuda Firewall.

3. Set up DNS for Internal Clients (Split DNS) Make your internal DNS server forward queries to the Barracuda Firewall. Configure split DNS.

4. Add More DNS Records Add more DNS records for web servers and email servers.

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5. Update Your Domain Registrar Tell the internet that your domain exists or has changed.

6. Test Test external access.

1. Enable Authoritative DNS on the Barracuda Firewall

Go to the NETWORK > Authoritative DNS page and enable Authoritative DNS. In the DNS Servers table, you can view a list of the links that are configured with the DNS Server service on the NETWORK > IP

page.

Configuration

2. Create One or More Domains

To define a domain:

On the NETWORK > Authoritative DNS page, click Add New Domain. Enter the domain name, and define TTL and zone transfer settings. Click Create.

You should see that the following records have been created:

Start of Authority (SOA)

Name Server (NS) — One NS record for each name server in the DNS Servers table is generated.

Address (A) — One A record is created for each name server in the DNS Servers table.

The DNS records are created with typical default values. To view and edit all of the values for each record, click E next to the record in the section.

dit DNS Records

To configure more than one external IP address for a domain:

On the NETWORK > Authoritative DNS page, edit the A record for the hostname. On the dialog that appears, in the IP Addresses table, specify the IP addresses to be used in response to external DNS queries.

The IP Addresses table is the list of IP addresses which can be used to reach this host name. When asked for the A record, the Barracuda Firewall rotates through this list of IP addresses, varying which IP address appears first in the returned list in round robin fashion. If an interface is not available, its IP address will not be returned in the list.

Add multiple IP addresses to achieve inbound link balancing and failover. Enter Local Network IP addresses, if they exist, for internal DNS queries (more about this in Step 3).

For each external IP address, in the Links column, select the WAN link from the drop down. Enter the address in the WAN IP Address field. Click to add the entry. Save your changes when complete.+

3. Set up DNS for Internal Clients (Split DNS)

The Barracuda Firewall supports a split DNS infrastructure. If you are using the same domain name for internally and externally accessible resources, internal (trusted) network clients receive the internal IP address of the resource and external clients receive the external address. To direct internal and external requests to different IP addresses for the same namespace:

On the NETWORK > IP Configuration page, add (or verify that you have added) a static trusted interface with the DNS Server service.

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For each hostname that is used both internally and externally, add one or more internal addresses: On the NETWORK > Authoritative DNS page, edit the A record for the hostname.

On the dialog that appears, in the IP Addresses table, specify the local IP addresses to be used in response to internal DNS queries. For each local address:

In the Links column, select INTERNAL ONLY to use a local IP address for this host name. In the Local Network column, type the local IP address for this host name.

Click +.

Save your changes when complete.

If you have an internal DNS server, configure it to forward queries to the interface in step 1.

Using an internal network client, try to access each hostname and verify that you are directed to the correct site.

4. Add More DNS Records

Add more DNS records to your domains to match your configuration. For example, each email server needs an MX record and a corresponding A record. Each web server needs an A record.

If you have externally reachable IP addresses that are not tied to any interface, such as ARIN networks, create an A record for each one. In the Links list, select ANY.

5. Update Your Domain Registrar

If you have not registered your domain name, register it with a domain name registrar like GoDaddy.com or register.com. Make the NS records of the domain point to your static WAN IP addresses. If your domain name is already registered, contact your registrar to update the NS records of the domain to point to your static WAN IP addresses. Remove records that reference any domains that are now delegated to the Barracuda Firewall.

Hosting a Subdomain

If your domain is hosted at your ISP or elsewhere and you want to delegate a subdomain to be resolved by the Barracuda Firewall, add some records to the zone file of the domain where it is stored at the registrar. If

the domain is example.com, and you want to host my.example.com and you have two name servers ns1 and ns

, add these lines, using the actual IP addresses of your name servers:

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my IN NS ns1

my IN NS ns2

ns1 IN A 216.101.241.181

ns2 IN A 192.0.2.2

From a host on the Internet, run nslookup on your domain names and verify that the expected IP addresses are returned. Depending on the change and how long the various resolvers cache DNS responses, it may take some time for your changes to be noted throughout the Internet. For example, it may take a day before a new domain name is accessible via the Internet. If a domain name was previously registered and the DNS record is modified, any server on the Internet that has the previous information will not get the update until the TTL of the original record has passed.

Back to Configuring Authoritative DNS.

Cloud Features

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