71 lines
4.8 KiB
HTML
71 lines
4.8 KiB
HTML
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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html
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PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html lang="en-us" xml:lang="en-us">
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<head>
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<meta name="DC.Type" content="concept" />
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<meta name="DC.Title" content="DNS-based load balancing" />
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<meta name="abstract" content="You can use DNS-based load balancing for your inbound workload. If load balancing is needed for local clients, use DNS load balancing." />
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<meta name="description" content="You can use DNS-based load balancing for your inbound workload. If load balancing is needed for local clients, use DNS load balancing." />
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<meta name="DC.Relation" scheme="URI" content="rzajwloadbasics.htm" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 1998, 2006" />
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<meta name="DC.Rights.Owner" content="(C) Copyright IBM Corporation 1998, 2006" />
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<meta name="DC.Format" content="XHTML" />
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<meta name="DC.Identifier" content="rzajwdnsrr" />
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<!-- All rights reserved. Licensed Materials Property of IBM -->
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<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
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<link rel="stylesheet" type="text/css" href="./ic.css" />
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<title>DNS-based load balancing</title>
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</head>
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<body id="rzajwdnsrr"><a name="rzajwdnsrr"><!-- --></a>
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<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">DNS-based load balancing</h1>
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<div><p>You can use DNS-based load balancing for your inbound workload.
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If load balancing is needed for local clients, use DNS load balancing.</p>
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<p>DNS-based load balancing is used for inbound load balancing. Multiple host
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IP addresses are configured in DNS for a single host server name. DNS alternates
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the host IP address returned to a successive client host name resolution request.
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An advantage to this type of load balancing is that it is a common DNS function.
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Disadvantages to this solution are that IP addresses can be cached by a client
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and it is a connection-based solution, not a load-based solution.</p>
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<p>The first way to achieve load balancing is to use a DNS function to pass
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out multiple addresses for the same system name. The DNS will serve a different
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IP address each time a request is made for the address record for your system
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name. In the following example, each address corresponds to a different system.
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This allows you to provide load balancing across two separate systems. In
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the case of clients on the private networks, they receive a different address
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for each request. This is a common DNS function. Notice that the public DNS
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also has two address entries. These addresses are translated using static
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NAT so that if you are on the Internet, you can reach the two systems.</p>
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<br /><img src="rzajw518.gif" alt="DNS-based load balancing" /><br /><p>If your programs depend on getting to a specific system or depend on returning
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to the same system after the initial connection, the Web pages and site should
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be coded to send a different system name after the first contact is made.
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Additional DNS entries can be added for MyServer1 208.222.150.10 and MyServer2
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208.222.150.11. By doing this, the Web sites, for example, can point to MyServer2
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after the first contact. This type of load balancing provides balancing by
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the connection request. In most cases, after you have resolved
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the address the client caches the address and will not ask again. This type
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of load balancing does not consider the amount of traffic going to each system.
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Note that this type of load balancing only considers inbound traffic and also
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that you can have two adapters on one system rather than one adapter on two
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systems.</p>
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</div>
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<div>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="rzajwloadbasics.htm" title="Workload balancing is redistributing network traffic and workload of heavily accessed machines across multiple processors, multiple interface adapters, or multiple host servers.">TCP/IP workload balancing methods</a></div>
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</div>
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<div class="relconcepts"><strong>Related concepts</strong><br />
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<div><a href="rzajwstatic.htm" title="Static NAT can use inbound connections from a public network into a private network.">Static NAT</a></div>
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</div>
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</div>
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</body>
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</html>
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