The 3DNS® Controller is a wide area load distribution solution. It works in tandem with BIG/ip® Server Array Controllers, other server array controllers, and single network servers to intelligently allocate Internet and intranet service requests across a geographically distributed array of network servers. The 3DNS Controller provides intelligent name resolution and adds load balancing intelligence to the latest BIND technology. Using the 3DNS Controller, you can provide clients with optimal performance, the most current data, safe data access, high availability, and protection from failed systems.
Figure 1.1 shows how 3DNS Controllers fit into a global network.
The network in Figure 1.1 uses the following configuration:
Note: Some countries do not allow data encryption. An international version of the 3DNS Controller is available for these situations. For more information, see Working with international versions, on page 2-15 .
With 3DNS Controllers properly implemented on a geographically dispersed network, the network becomes more efficient, reliable, and scalable.
3DNS Controllers increase efficiency of a network in the following ways:
It is important to ensure that clients have access to the services they need at all times. The following features ensure the reliability of a network:
3DNS Controllers provide the flexibility to effectively manage changing network demands. With 3DNS Controllers in place, your network becomes more scalable by:
The following features are new in version 1.0.6 of the 3DNS Controller.
The 3DNS Controller now supports three hierarchical load balancing methods. For each pool in a wideip statement, you can specify a preferred method, an alternate method, and a fallback method. See The wide IP statement, on page 7-21 .
3DNS Controller can now control access to specific data centers, based on the IP address of the requesting local DNS. See Topology-based access control, on page 5-15 .
The new Topology load balancing mode distributes connections based on the proximity of a local DNS to a particular data center. See page 5-21 . The topology mode can also be incorporated into the Quality of (QOS) load balancing mode.
Using the port_list parameter, you can configure a wide IP so that connections are not sent to a given address unless all listed services are available. This feature is especially useful for e-commerce transactions. See E-commerce, on page 5-22 .
3DNS Controller includes a new big3d utility for all versions of BIG/ip Controller.
The 3DNS Web Administration tool now includes an Administration area where you can change the 3DNS Controller configuration and control statistics collection. The original statistics screens also contain new information in several areas. See Chapter 6, Web Administration .
The 3DNS Maintenance menu includes several new commands:
3DNS Controller has three new iQuery options:
3DNS Controller now has advanced path probing schemes, which determine path attributes such as round trip time and packet completion rate. See Understanding probing, on page 2-21 .
You can now store your original wideip.conf file separately from a wideip.conf file that stores current path and local DNS information. See Working with static and dynamic wideip.conf files, on page C-2 .
You now have the option of storing zone files in a /var/namedb directory, which offers substantially more storage space than the /etc/namedb directory. See Storing zone files, on page 3-7 .
In previous versions of 3DNS Controller, the First-Time Boot utility ran at start up if the system did not detect the /etc/wideip.conf file. However, in the current version, the First-Time Boot utility is triggered only if the /etc/netstart file is not found. The /etc/wideip.conf file is no longer used to trigger or prevent the First-Time Boot utility from running at start up. If you are upgrading from an earlier version, you must change the appropriate lines in the /etc/rc file to take advantage of this change. See Upgrading an earlier version, on page 3-4 .
You can now use shell style comments (also known as Perl style comments) in the bigips.txt and 3dns.txt files. See File location, on page D-20 .
3DNS Controller now supports versions for international distribution. See page 2-15 .
You can use the new watchdog-named utility to start and monitor the named process. See watchdog-named, on page D-3 . It is important to note that when your 3DNS Controller is using watchdog-named, you cannot use ndc to stop, start, or restart named. Instead, you must use 3ndc. See 3ndc, on page D-5 .
This section describes the typographic and terminology conventions used in this manual.
Understanding these conventions is especially useful in learning command syntax.
Certain characters are used to indicate whether a parameter is mandatory or optional, or whether you can use one parameter or another.
The courier typeface is used to distinguish user input and computer output from explanatory text.
The following terms, used in this manual, require some explanation:
The term host machine refers to an individual network server or server array controller other than the BIG/ip Controller.
You can configure a 3DNS Controller to be a data collector or a data copier:
The Domain Name System (DNS) is a distributed database that maps IP addresses to host names. All DNS servers (DNS and 3DNS) resolve names.
The terms primary and secondary are used to differentiate between DNS systems that maintain authoritative zone information, and DNS systems that copy zone information from other DNS systems:
This manual assumes that you have general knowledge of DNS. For complete documentation of DNS, you can refer to O'Reilly & Associates' book DNS and BIND (second or third edition). When you review DNS documentation that covers BIND 8, you will notice that BIND 8 now uses the terms master and slave instead of primary and secondary.
Note: You can configure a 3DNS Controller so that it handles DNS name resolution and authoritative zone information, in addition to metrics collection. In this case, the 3DNS machine is the data collector as well as the primary DNS.
The term "VIP" has been replaced by virtual server, and it is used to refer to a specific combination of a virtual IP address and a virtual port number managed by a BIG/ip Controller or other host machine. Throughout this manual, virtual servers managed by BIG/ip Controllers are represented by vsb, and virtual servers managed by other host machines are represented by vsh.
The term node refers to a specific combination of a node address and a node port number, which is managed by the BIG/ip Controller. A BIG/ip Controller maps each virtual server to one or more nodes. In the 3DNS Web Administration tool, Nodes Up denotes the number of nodes that are currently available for a given virtual server. The 3DNS Controller monitors and collects data for nodes that are managed only by BIG/ip Controllers.
The term local DNS refers to a DNS server that makes name resolution requests on behalf of a client. From the 3DNS Controller's perspective, the local DNS is the source of the name resolution request.