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https://issues.apache.org/jira/browse/HADOOP-8134?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Harsh J resolved HADOOP-8134.
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Resolution: Not A Problem
Assignee: (was: Harsh J)
This hasn't proven as a problem in late. Closing as stale.
> DNS claims to return a hostname but returns a PTR record in some cases
> ----------------------------------------------------------------------
>
> Key: HADOOP-8134
> URL: https://issues.apache.org/jira/browse/HADOOP-8134
> Project: Hadoop Common
> Issue Type: Bug
> Components: util
> Affects Versions: 0.23.0
> Reporter: Harsh J
> Priority: Minor
>
> Per Shrijeet on HBASE-4109:
> {quote}
> If you are using an interface anything other than 'default' (literally that
> keyword) DNS.java's getDefaultHost will return a string which will have a
> trailing period at the end. It seems javadoc of reverseDns in DNS.java (see
> below) is conflicting with what that function is actually doing.
> It is returning a PTR record while claims it returns a hostname. The PTR
> record always has period at the end , RFC:
> http://irbs.net/bog-4.9.5/bog47.html
> We make call to DNS.getDefaultHost at more than one places and treat that as
> actual hostname.
> Quoting HRegionServer for example
> String machineName = DNS.getDefaultHost(conf.get(
> "hbase.regionserver.dns.interface", "default"), conf.get(
> "hbase.regionserver.dns.nameserver", "default"));
> We may want to sanitize the string returned from DNS class. Or better we can
> take a path of overhauling the way we do DNS name matching all over.
> {quote}
> While HBase has worked around the issue, we should fix the methods that
> aren't doing what they've intended.
> 1. We fix the method. This may be an 'incompatible change'. But I do not know
> who outside of us uses DNS classes.
> 2. We fix HDFS's DN at the calling end, cause that is affected by the
> trailing period in its reporting back to the NN as well (Just affects NN->DN
> weblinks, non critical).
> For 2, we can close this and open a HDFS JIRA.
> Thoughts?
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