Troubleshooting Application Issues

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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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Lab Info

Level

Advanced

Last updated

Sep 25, 2025

Duration

1h 30m

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
```
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
```
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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