Use Case 2: ISP Tenant Uses DNS Proxy to Handle DNS Resolution for Security Policies, Reporting, and Services within its Virtual System

In this use case, multiple tenants (ISP subscribers) are defined on the firewall and each tenant is allocated a separate virtual system (vsys) and virtual router in order to segment its services and administrative domains. The following figure illustrates several virtual systems within a firewall.

Each tenant has its own server profiles for Security policy rules, reporting, and management services (such as email, Kerberos, SNMP, syslog, and more) defined in its own networks.

For the DNS resolutions initiated by these services, each virtual system is configured with its own DNS Proxy Object to allow each tenant to customize how DNS resolution is handled within its virtual system. Any service with a

Location

will use the DNS Proxy object configured for the virtual system to determine the primary (or secondary) DNS server to resolve FQDNs, as illustrated in the following figure.

For each virtual system, specify the DNS Proxy to use.
Select
Device
Virtual Systems
and
Add
the
ID
of the virtual system (range is 1-255), and an optional
Name
, in this example, Corp1 Corporation.
On the
General
tab, choose a
DNS Proxy
or create a new one. In this example, Corp1 DNS Proxy is selected as the proxy for Corp1 Corporation’s virtual system.
For
Interfaces
, click
Add
. In this example, Ethernet1/20 is dedicated to this tenant.
For
Virtual Routers
, click
Add
. A virtual router named Corp1 VR is assigned to the virtual system in order to separate routing functions.
Click
OK
.
Configure a DNS Proxy and a server profile to support DNS resolution for a virtual system.
Select
Network
DNS Proxy
and click
Add
.
Click
Enable
and enter a
Name
for the DNS Proxy.
For
Location
, select the virtual system of the tenant, in this example, Corp1 Corporation (vsys6). (You could choose the
Shared
DNS Proxy resource instead.)
For
Server Profile
, choose or create a profile to customize DNS servers to use for DNS resolutions for this tenant’s security policy, reporting, and server profile services.
If the profile is not already configured, in the
Server Profile
field, click
DNS Server Profile
to Configure a DNS Server Profile.
The DNS server profile identifies the IP addresses of the primary and secondary DNS server to use for management DNS resolutions for this virtual system.
Also for this server profile, optionally configure a
Service Route IPv4
and/or a
Service Route IPv6
to instruct the firewall which
Source Interface
to use in its DNS requests. If that interface has more than one IP address, configure the
Source Address
also.
Select the
Advanced
tab. Ensure that
Cache
is enabled and
Cache EDNS Responses
is enabled (both are enabled by default). This is required if the DNS proxy object is used under
Device
Virtual Systems
vsys
General
DNS Proxy
.
Click
OK
.
Click
OK
and
Commit
.
Optional advanced features such as split DNS can be configured using
DNS Proxy Rules
. A separate DNS server profile can be used to redirect DNS resolutions matching the
Domain Name
in a
DNS Proxy Rule
to another set of DNS servers, if required. Use Case 3 illustrates split DNS.
If you use two separate DNS server profiles in the same DNS Proxy object, one for the DNS Proxy and one for the DNS proxy rule, the following behaviors occur:
If a service route is defined in the DNS server profile used by the DNS Proxy, it takes precedence and is used.
If a service route is defined in the DNS server profile used in the DNS proxy rules, it is not used. If the service route differs from the one defined in the DNS server profile used by the DNS Proxy, the following warning message is displayed during the
Commit
process:
Warning: The DNS service route defined in the DNS proxy object is different from the DNS proxy rule’s service route. Using the DNS proxy object’s service route.
If no service route is defined in any DNS server profile, the global service route is used if needed.