Manual Chapter : 3-DNS Admin Guide v4.5.10: Introduction

Applies To:

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3-DNS Controller versions 1.x - 4.x

  • 4.5.14, 4.5.13, 4.5.12, 4.5.11, 4.5.10
Manual Chapter



Getting started

The 3-DNS Administrator Guide is designed to help you quickly install and configure the 3-DNS® Controller to manage your wide-area network traffic and DNS. The Administrator Guide contains the following chapters:

  • Planning the 3-DNS Configuration
    This chapter describes the network and configuration planning you need to do before you install the 3-DNS Controller in your network.

  • Using the Setup Utility
    This chapter describes the Setup utility and its functions. The Setup utility runs automatically the first time you turn on the 3-DNS Controller.

  • Post-Setup Tasks
    This chapter describes the base network, which includes the IP addresses, VLANs, and network interfaces on the 3-DNS Controller.

  • Essential Configuration Tasks
    This chapter describes the software configuration tasks you must complete, regardless of the type of wide-area traffic management you want to configure.

  • Configuring a Globally Distributed Network
    This chapter describes the tasks you complete to set up a globally distributed network.

  • Configuring a Content Delivery Network
    This chapter describes the tasks you complete to set up a network that includes a CDN provider.

  • Working with Quality of Service
    This chapter describes the components of the Quality of Service load balancing mode.

  • Working with Global Availability Load Balancing
    This chapter describes the components of the Global Availability load balancing mode.

  • Adding a 3-DNS Controller to an Existing Network
    This chapter describes the tasks you complete to configure an additional 3-DNS Controller in a network that already contains one or more 3-DNS Controllers.

Choosing a configuration tool

The 3-DNS Controller provides several web-based and command line administrative tools that make for easy setup and configuration. Use the following overview to help you decide when each utility is best used.

Setup utility

The Setup utility is a wizard that walks you through the initial system setup. The utility helps you quickly define basic system settings, such as a root password and the IP addresses for the interfaces that connect the 3-DNS Controller to the network. The Setup utility also helps you configure access to the 3-DNS web server, which hosts the web-based Configuration utility, as well as the NameSurferTM application that you can use for DNS zone file management.

Configuration utility

The Configuration utility is a web-based application that you use to configure and monitor the 3-DNS Controller. Using the Configuration utility, you can define the load balancing configuration along with the network setup, including data centers, sync groups, and servers used for load balancing and path probing. In addition, you can configure advanced features such as topology settings and SNMP agents. The Configuration utility also monitors network traffic, current connections, load balancing statistics, performance metrics, and the operating system itself. The home screen of the Configuration utility provides convenient access to downloads such as the SNMP MIB, and documentation for third-party applications such as NameSurfer.

NameSurfer application

The NameSurfer application is a third-party application that automatically configures DNS zone files associated with domains handled by the 3-DNS Controller. You can use NameSurfer to configure and maintain additional DNS zone files on a 3-DNS Controller that runs as a primary DNS server. The Configuration utility provides direct access to the NameSurfer application, as well as the corresponding documentation for the application. Please note that your license allows you to manage a maximum of 100 IP addresses in the NameSurfer application. For more information, refer to the end-user license agreement included in your product shipment.

3-DNS Maintenance menu

The 3-DNS Maintenance menu is a command line utility that runs scripts which assist you in configuration and administrative tasks, such as installing the latest version of the big3d agent on all your systems, or setting up encrypted communications in the network. You can use the 3-DNS Maintenance menu from a console connection, from a remote shell connection, or from the MindTerm SSH Client in the Configuration utility.

Browser support

The Configuration utility, which provides web-based access to the 3-DNS configuration and features, supports the following browser versions:

  • Netscape Navigator 4.7x

  • Microsoft Internet Explorer, version 5.0, 5.5, or 6.0

Using the Administrator Kit

The 3-DNS Administrator Kit provides simple steps for quick, basic configuration, and also provides detailed information about more advanced features and tools, such as the 3dnsmaint command line utility. The following printed documentation is included with the 3-DNS unit.

  • Configuration Worksheet
    This worksheet provides you with a place to plan the basic configuration for the 3-DNS Controller.

The following guides are available in PDF format from the CD-ROM provided with the 3-DNS Controller. These guides are also available from the home screen of the Configuration utility.

  • Platform Guide
    This guide includes information about the physical 3-DNS unit. It also contains important environmental warnings.

  • 3-DNS Administrator Guide
    The 3-DNS Administrator Guide provides examples of common wide-area load balancing solutions supported by the 3-DNS Controller. For example, you can find everything from a basic DNS request load balancing solution to a more advanced content acceleration load balancing solution. This guide also covers general network administration issues, such as installing the hardware and setting up the networking configuration.

  • 3-DNS Reference Guide
    The 3-DNS Reference Guide provides basic descriptions of individual 3-DNS objects, such as wide IPs, pools, virtual servers, load balancing modes, the big3d agent, resource records, and production rules. It also provides syntax information for 3dnsmaint commands, configuration utilities, the wideip.conf file, and system utilities.

Stylistic conventions

To help you easily identify and understand certain types of information, this documentation uses the following stylistic conventions.

Using the solution examples

All examples in this documentation use only non-routable IP addresses. When you set up the solutions we describe, you must use IP addresses suitable to your own network in place of our sample IP addresses.

Identifying new terms

When we first define a new term, the term is shown in bold italic text. For example, a wide IP is a mapping of a fully-qualified domain name to a set of virtual servers that host the domain's content.

Identifying references to products

We refer to all products in the BIG-IP product family as the BIG-IP system. We refer to the 3-DNS Controller and the 3-DNS module as the 3-DNS Controller. If specific configuration information relates to a specific platform, we note the platform.

Identifying references to objects, names, and commands

We apply bold text to a variety of items to help you easily pick them out of a block of text. These items include web addresses, IP addresses, utility names, and portions of commands, such as variables and keywords. For example, the nslookup command requires that you include at least one <ip_address> variable.

Identifying references to other documents

We use italic text to denote a reference to another document. In references where we provide the name of a book as well as a specific chapter or section in the book, we show the book name in bold, italic text, and the chapter/section name in italic text to help quickly differentiate the two. For example, you can find information about topology in the 3-DNS Reference Guide, Chapter 3, Topology .

Identifying command syntax

We show actual, complete commands in bold Courier text. Note that we do not include the corresponding screen prompt, unless the command is shown in a figure that depicts an entire command line screen. For example, the following command sets the 3-DNS Controller load balancing mode to Round Robin:

lb_mode rr

Table 1.1 explains additional special conventions used in command line syntax.


Item in text



Continue to the next line without typing a line break.

< >

You enter text for the enclosed item. For example, if the command has <your name>, type in your name.


Separates parts of a command.

[ ]

Syntax inside the brackets is optional.


Indicates that you can type a series of items.


What is the 3-DNS Controller?

A 3-DNS Controller is a network appliance that monitors the availability and performance of global resources, and uses that information to manage network traffic patterns. The 3-DNS Controller uses load balancing algorithms, topology-based routing, and production rules to control and distribute traffic according to specific policies. The system is highly configurable, and its web-based and command line configuration utilities allow for easy system setup and monitoring.

The 3-DNS Controller provides a variety of features that meet special needs. For example, with this product you can:

  • Configure a content delivery network with a CDN provider

  • Guarantee multiple port availability for e-commerce sites

  • Ensure wide-area persistence by maintaining a mapping between an local DNS server and a virtual server in a wide IP pool

  • Direct local clients to local servers for globally-distributed sites using Topology load balancing

  • Change the load balancing configuration according to current traffic patterns or time of day

  • Customize load balancing modes

  • Set up load balancing among BIG-IP systems, EDGE-FX Caches, and other load-balancing hosts

  • Monitor real-time network conditions

Internet protocol and network management support

The 3-DNS Controller supports both the standard DNS protocol and the 3-DNS iQuery protocol (a protocol used for collecting dynamic load balancing information). The 3-DNS Controller also supports administrative protocols, such as Simple Network Management Protocol (SNMP), and Simple Mail Transfer Protocol (SMTP) (outbound only), for performance monitoring and notification of system events. For administrative purposes, you can use SSH, RSH, Telnet, and FTP. The Configuration utility supports HTTPS, for secure web browser connections using SSL, as well as standard HTTP connections.

The proprietary 3-DNS SNMP agent allows you to monitor status and current traffic flow using popular network management tools. The 3-DNS SNMP agent provides detailed data such as current connections being handled by each virtual server.

Security features

The 3-DNS Controller offers a variety of security features that can help prevent hostile attacks on your site or equipment.

  • Secure administrative connections
    The 3-DNS Controller supports Secure Shell (SSH) administrative connections using the Mindterm SSH Client, for browser-based remote administration, and SSH for remote administration from the command line. The 3-DNS web server, which hosts the web-based Configuration utility, supports SSL connections as well as user authentication.

  • Secure iQuery communications
    Crypto versions of the 3-DNS Controller also support Blowfish encryption for iQuery communications between the 3-DNS Controller and other systems running the big3d agent.

  • TCP wrappers
    TCP wrappers provide an extra layer of security for network connections.

Configuration scalability

The 3-DNS Controller is a highly scalable and versatile solution. You can configure the 3-DNS Controller to manage up to several hundred domain names, including full support of domain name aliases. The 3-DNS Controller supports a variety of media options, including Fast Ethernet, and Gigabit Ethernet; the 3-DNS Controller also supports multiple network interface cards that can provide redundant or alternate paths to the network.


If you use NameSurfer to manage your DNS zone files, you can configure only up to 100 IP addresses and domain names.

System synchronization options

The 3-DNS Controller sync group feature allows you to automatically synchronize configurations from one 3-DNS Controller to any other 3-DNS Controller or Link Controller in the network, simplifying administrative management. The synchronization feature offers a high degree of administrative control. For example, you can set the 3-DNS Controller to synchronize a specific configuration file set, and you can also set which 3-DNS Controllers in the network receive the synchronized information and which ones do not.

Configuring data collection for server status and network path data

The 3-DNS platform includes the big3d agent, which is an integral part of 3-DNS load balancing. The big3d agent continually monitors the availability of the servers that the 3-DNS Controller load balances. It also monitors the integrity of the network paths between the servers that host the domain, and the various local DNS servers that attempt to connect to the domain. The big3d agent runs on any of the following platforms: 3-DNS Controller, BIG-IP systems, EDGE-FX Cache, and GLOBAL-SITE Controller. Each big3d agent broadcasts its collected data to all of the 3-DNS Controllers in your network, ensuring that all 3-DNS Controllers work with the latest information.

The big3d agent offers a variety of configuration options that allow you to choose the data collection methods you want to use. For example, you can configure the big3d agent to track the number of router hops (intermediate system transitions) along a given network path, and you can also set the big3d agent to collect host server performance information using the SNMP protocol. For further details on the big3d agent, refer to the 3-DNS Reference Guide, Chapter 5, Probing and Metrics Collection .

Redundant system configurations

A redundant system is essentially a pair of 3-DNS units, with one operating as the active unit that responds to DNS queries, and the other one operating as the standby unit. If the active unit fails, the standby unit takes over and begins to respond to DNS queries while the other 3-DNS unit restarts and becomes the standby unit.

The 3-DNS Controller actually supports two methods of checking the status of the peer system in a redundant system:

  • Hardware-based fail-over
    In a redundant system that has been set up with hardware-based fail-over, the two units in the system are connected to each other directly using a fail-over cable attached to the serial ports. The standby unit checks on the status of the active unit once every second using this serial link.

  • Network-based fail-over
    In a redundant system that has been set up with network-based fail-over, the two units in the system communicate with each other across an Ethernet network instead of going across a dedicated fail-over serial cable. The standby unit checks on the status of the active unit once every second using the Ethernet.


In a network-based fail-over configuration, the standby 3-DNS unit immediately takes over if the active unit fails. If a client has queried the failed 3-DNS unit, and not received an answer, it automatically re-issues the request (after 5 seconds) and the standby unit, functioning as the active unit, responds.


Monitoring the 3-DNS Controller and the network

The 3-DNS Controller includes sophisticated monitoring tools to help you monitor the 3-DNS Controller, the traffic it manages, and the Internet. The following monitoring tools are available on the 3-DNS Controller: the Statistics screens, the Internet Weather Map, and the Network Map. All of these tools are in the Configuration utility.

Comparing a 3-DNS Controller to a BIG-IP system

A 3-DNS Controller load balances traffic for a globally-distributed network, and a BIG-IP system load balances traffic for a local area network. While both systems provide load balancing, one of the significant differences between the BIG-IP system and the 3-DNS Controller is that the 3-DNS Controller responds to DNS requests issued by an LDNS on behalf of a client, while the BIG-IP system provides connection management between a client and a back-end server.

Once the 3-DNS Controller returns a DNS answer to an LDNS, the conversation between the LDNS and the 3-DNS Controller ends, and the client connects to the IP address returned by the 3-DNS Controller. Unlike the 3-DNS Controller, the BIG-IP system sits between the client and the content servers. It manages the client's entire conversation with the content server.

Finding help and technical support resources

You can find additional technical documentation about the 3-DNS Controller in the following locations:

  • Release notes
    Release notes for the 3-DNS Controller are available from the home screen of the Configuration utility. The release note contains the latest information for the current version, including a list of new features and enhancements, a list of fixes, and a list of known issues.

  • Online help for 3-DNS features
    You can find help online in three different locations:

    • The Configuration utility home screen has PDF versions of the guides included in the Administrator Kit. 3-DNS software upgrades may replace the guides with updated versions as appropriate.

    • The Configuration utility has online help for each screen. Click the Help button on the toolbar.

    • Individual commands have online help, including command syntax and examples, in standard UNIX man page format. Type the command followed by -h or -help, and the 3-DNS Controller displays the syntax and usage associated with the command. You can also type man <command> to display the man page for the command.

  • Third-party documentation for software add-ons
    The Configuration utility contains online documentation for the third-party software included with the 3-DNS Controller, including the NameSurfer application.

  • Technical support through the World Wide Web
    The F5 Networks Technical Support web site,, provides the latest technical notes, answers to frequently asked questions, updates for the Administrator Kit (in PDF format), updates for the release notes, and the AskF5 natural language question and answer engine.


All references to hardware platforms in this guide refer specifically to systems supplied by F5 Networks, Inc. If your hardware was supplied by another vendor and you have hardware-related questions, please refer to the documentation from that vendor.