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| Problem | Having a bad DNS configuration could cause WebSphere to run extremely slow. Every network lookup to the local host would have to wait for a 5 second timeout. | | | | Solution | If the DNS configuration of a host is not correct, which happens frequently when DHCP is used or if the network for a system is not configured correctly, host lookups by name could take 5 seconds per try even when resolving the local host...To check that: create a file called checkdns.java and add this code to it: import java.net.*; import java.io.*;
public class checkdns { public static void main(String args[]) { try { InetAddress local= InetAddress.getLocalHost(); System.out.println("InetAddress = " + local + ", using getLocalHost()");
InetAddress local2 = InetAddress.getByName(local.getHostAddress()); System.out.println("InetAddress = " + local2 + ", using getByName(local.getHostAddress()");
if (local2.getHostName().equals(local2.getHostAddress())) System.out.println("=====> Reverse DNS problem! " + " WebSphere performance will suffer."); else System.out.println("DNS configuration appears correct.");
} catch (Exception e ) { System.out.println("Exception: " + e + " caught!"); e.printStackTrace(); } } } Now save the file and compile it by typing: javac checkdns.javaTo run it simply type: java checkdnsIf the message Reverse DNS problem! is displayed then domain name server is not setup correctly on this host's network configuration. To correct that the host administrator must add a name server to the network configuration following the network guidelines for the type of host OR hostnames, including the local hostname, or it may be added manually to the hosts file. | |
| | | Product Alias/Synonym | WebSphere
WAS | |
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Product categories: Software, Application Servers, Distributed Application & Web Servers, WebSphere Application Server, Servlet Engine/Web Container Operating system(s): All Platforms Software version: 3.0.1, 3.0.2, 3.5, 3.5.1, 3.5.2 Software edition: WebSphere Advanced Reference #: 1006454 IBM Group: Software Group Modified date: 2001-03-19
(C) Copyright IBM Corporation 2000, 2004. All Rights Reserved.
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