Specifications

Chapter 3: Configuring the Barracuda Link Balancer 33
Step 3 - Set up DNS for Internal Clients
If you have an internal DNS server, configure it to forward queries to the LAN IP address of the
Barracuda Link Balancer.
If the built-in firewall of the Barracuda Link Balancer is enabled:
As already described, when you create a new domain, the Barracuda Link Balancer looks for existing
1:1 NAT and port forwarding rules that include names in the Hostname field that have appear to be
relevant and creates an A record for each matching rule, including both external and internal
addresses.
In some cases, this mapping will not reflect your configuration. Using an internal network client, try
to access a hostname for a resource that is available both internally and externally. If the test fails, edit
the A record for the unresolved hostname. The
DNS Record page will appear. In the IP Addresses
table, add addresses to the Local Network column to be used in response to internal DNS queries.
If the built-in firewall of the Barracuda Link Balancer is disabled:
The Barracuda is not able to derive internal a mapping between external and internal addresses if the
firewall is disabled. If you want internal addresses to be served, edit the A record for the hostname of
each resource that is available both internally and externally. The
DNS Record page will appear. In
the IP Addresses table, add addresses to the Local Network column to be used in response to internal
DNS queries.
Using an internal network client, test your changes by trying to access the resource using its hostname.
Step 4 - Add More DNS Records
Add more DNS records to your domain(s) 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:
• If the address is not routed through the Barracuda Link Balancer, select CUSTOM in the
Links
list.
• If the address is routed through the Barracuda Link Balancer, select ANY in the
Links list.
Step 5 - Update Your Domain Registrar
If you haven't already 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 the domain or
domains that are now delegated to the Barracuda Link Balancer.
Hosting a sub-domain
If your domain is hosted at your ISP or elsewhere and you want to delegate a sub-domain to be
resolved by the Barracuda Link Balancer, you will have to 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 ns2, add these lines, using the actual IP
addresses of your name servers: