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Troubleshooting Application Issues

In this exercise, you will troubleshoot three different application issues. **This course is not approved or sponsored by Red Hat.**

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Labs

Path Info

Level
Clock icon Advanced
Duration
Clock icon 1h 30m
Published
Clock icon Apr 02, 2019

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Table of Contents

  1. Challenge

    Troubleshoot and resolve issues using the dig, host, and nslookup commands.

    Attempt to use dig to look up an IP for linuxacademy.com:

    dig linuxacademy.com
    

    Use ldd to view the libraries used by dig:

    ldd $(which dig)
    

    libdns.so.1102 is missing. Use yum to find a package that installs this library:

    yum provides */libdns.so.1102
    

    Reinstall the bind-libs-lite package:

    yum reinstall -y bind-libs-lite
    

    Attempt to use dig to look up an IP for linuxacademy.com:

    dig linuxacademy.com
    
  2. Challenge

    Assess the application /root/memleak_test_app for a memory leak.

    Install valgrind:

    yum install -y valgrind
    

    Run valgrind against /root/test_app:

    valgrind ./memleak_test_app
    

    If the app has a memory leak, remove executable permissions:

    chmod -x /root/memleak_test_app
    
  3. Challenge

    Assess and resolve the issue with /root/example_app.

    Attempt to run the application:

    /root/example_app
    

    Install strace:

    yum install -y strace
    

    Run the application again using strace:

    strace /root/example_app
    

    Create the missing file:

    touch /etc/example.conf
    

    Run the application again:

    /root/example_app
    

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