HADOOP-16674. Fix when TestDNS.testRDNS can fail with ServiceUnavailableException

[ashutoshcipher]

Description of PR

Fix when TestDNS.testRDNS can fail with ServiceUnavailableException

JIRA - HADOOP-16674

For code changes:

• Does the title or this PR starts with the corresponding JIRA issue id (e.g. 'HADOOP-17799. Your PR title ...')?
• Object storage: have the integration tests been executed and the endpoint declared according to the connector-specific documentation?
• If adding new dependencies to the code, are these dependencies licensed in a way that is compatible for inclusion under ASF 2.0?
• If applicable, have you updated the LICENSE, LICENSE-binary, NOTICE-binary files?

[hadoop-yetus]

💔 -1 overall

Vote	Subsystem	Runtime	Logfile	Comment
+0 🆗	reexec	1m 4s		Docker mode activated.
			_ Prechecks _
+1 💚	dupname	0m 0s		No case conflicting files found.
+0 🆗	codespell	0m 0s		codespell was not available.
+0 🆗	detsecrets	0m 0s		detect-secrets was not available.
+1 💚	@author	0m 0s		The patch does not contain any @author tags.
+1 💚	test4tests	0m 0s		The patch appears to include 1 new or modified test files.
			_ trunk Compile Tests _
+1 💚	mvninstall	38m 59s		trunk passed
+1 💚	compile	23m 7s		trunk passed with JDK Private Build-11.0.15+10-Ubuntu-0ubuntu0.20.04.1
+1 💚	compile	20m 36s		trunk passed with JDK Private Build-1.8.0_312-8u312-b07-0ubuntu1~20.04-b07
+1 💚	checkstyle	1m 31s		trunk passed
+1 💚	mvnsite	2m 3s		trunk passed
+1 💚	javadoc	1m 43s		trunk passed with JDK Private Build-11.0.15+10-Ubuntu-0ubuntu0.20.04.1
+1 💚	javadoc	1m 16s		trunk passed with JDK Private Build-1.8.0_312-8u312-b07-0ubuntu1~20.04-b07
+1 💚	spotbugs	3m 8s		trunk passed
-1 ❌	shadedclient	5m 31s		branch has errors when building and testing our client artifacts.
			_ Patch Compile Tests _
+1 💚	mvninstall	1m 5s		the patch passed
+1 💚	compile	22m 22s		the patch passed with JDK Private Build-11.0.15+10-Ubuntu-0ubuntu0.20.04.1
+1 💚	javac	22m 22s		the patch passed
+1 💚	compile	20m 32s		the patch passed with JDK Private Build-1.8.0_312-8u312-b07-0ubuntu1~20.04-b07
+1 💚	javac	20m 32s		the patch passed
+1 💚	blanks	0m 0s		The patch has no blanks issues.
+1 💚	checkstyle	1m 25s		the patch passed
+1 💚	mvnsite	1m 54s		the patch passed
+1 💚	javadoc	1m 31s		the patch passed with JDK Private Build-11.0.15+10-Ubuntu-0ubuntu0.20.04.1
+1 💚	javadoc	1m 2s		the patch passed with JDK Private Build-1.8.0_312-8u312-b07-0ubuntu1~20.04-b07
+1 💚	spotbugs	3m 6s		the patch passed
-1 ❌	shadedclient	5m 4s		patch has errors when building and testing our client artifacts.
			_ Other Tests _
+1 💚	unit	19m 56s		hadoop-common in the patch passed.
+1 💚	asflicense	1m 31s		The patch does not generate ASF License warnings.
		179m 26s

Subsystem	Report/Notes
Docker	ClientAPI=1.41 ServerAPI=1.41 base: https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-4802/1/artifact/out/Dockerfile
GITHUB PR	#4802
Optional Tests	dupname asflicense compile javac javadoc mvninstall mvnsite unit shadedclient spotbugs checkstyle codespell detsecrets
uname	Linux 0dbddedad29f 4.15.0-191-generic #202-Ubuntu SMP Thu Aug 4 01:49:29 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux
Build tool	maven
Personality	dev-support/bin/hadoop.sh
git revision	trunk / 789befc
Default Java	Private Build-1.8.0_312-8u312-b07-0ubuntu1~20.04-b07
Multi-JDK versions	/usr/lib/jvm/java-11-openjdk-amd64:Private Build-11.0.15+10-Ubuntu-0ubuntu0.20.04.1 /usr/lib/jvm/java-8-openjdk-amd64:Private Build-1.8.0_312-8u312-b07-0ubuntu1~20.04-b07
Test Results	https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-4802/1/testReport/
Max. process+thread count	1649 (vs. ulimit of 5500)
modules	C: hadoop-common-project/hadoop-common U: hadoop-common-project/hadoop-common
Console output	https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-4802/1/console
versions	git=2.25.1 maven=3.6.3 spotbugs=4.2.2
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[ashutoshcipher]

@ayushtkn, Please help in reviewing the PR. Thanks.

[ashutoshcipher]

@ayushtkn - Please help in reviewing this PR. Thanks.

[ashutoshcipher]

@ayushtkn, Please help in reviewing. Thanks.

[ayushtkn]

LGTM

[ashutoshcipher]

Thanks @ayushtkn for reviewing and merging.