FAQ
Stefan,

Your setup is correct. I'll check to see what the behavior is with no
entries in /etc/resolv.conf and get back to you.

Thanks,

*Brian Burton*
*Customer Operations Engineer*
<http://www.cloudera.com>

On Thu, Jun 13, 2013 at 10:06 AM, Stefan wrote:

Brian,
thanks for your reply. I checked the logs and found that the java process
reads:
hostname = romeo
canonical name = romoe0.lan

Yes I am aware of this and I believe this is correct. I configured the
hostname as a non fully qualified name according to instructions here:

http://www.cloudera.com/content/cloudera-content/cloudera-docs/CDH4/4.2.0/CDH4-Installation-Guide/cdh4ig_topic_11_1.html

Of course I can rename the hostname to romeo0.lan

Should I do that? Still a bit confused, maybe I am missing something here.

btw: I have no search or domain entries in resolve.conf because I assumed
they are optinal.

Stefan

On Thursday, June 13, 2013 3:13:16 PM UTC+2, bdb wrote:

Stefan,

You're in luck, I just had this same question and one of our developers
(A.B.) provided some detailed information on this:

The DNS resolution check uses the Java InetAddress class (much like what
Hadoop daemons typically do) to:
1. get the local address (addr = InetAddress.getLocalHost()) and uses the
retrieved address to
2. get the hostname (addr.getHostName()) and the FQDN / canonicalHostName
(addr.getCanonicalHostName())
3. Verify that 'hostname' can be used to derive 'canonicalHostName' by
using the info in /etc/resolv.conf
-- 3a. If /etc/resolv.conf has an entry of the form "domain
isp.domain.name", 'hostname'.isp.domain.name **should be
'canonicalHostName' for the check to pass.
-- 3b. If /etc/resolv.conf has an entry of the form "search domain1.name
domain2.**name <http://domain2.name/> .. domainN.name",
'canonicalHostName' should be one of 'hostname'.domain1.name, 'hostname'.
domain2.name .. or 'hostname'.domainN.name

Here are a couple of things to check/verify:
- Check /etc/resolv.conf on the hosts that are not 'healthy'. See what
the domain and search lines are.romeo0.lan is not part of /etc/resolv.conf
on those hosts and/or different from what it is on the 'healthy' hosts.
- Look for an INFO message of the form ""hostname <hostname> differs from
the canonical name <canonicalname>" in the agent logs
(/var/log/cloudera-scm-agent/***.log) on the unhealthy hosts. That
should give you the exact names being used for the check performed in step
3 above.

Please let us know if this helps to determine the source of the health
check failure, or if you have any questions or need clarification on
anything.

Thanks,

*Brian Burton*
*Customer Operations Engineer*
<http://www.cloudera.com>

On Thu, Jun 13, 2013 at 8:10 AM, Stefan wrote:

Hello!

I receive the above mentioned error despite being quite sure my
configuration is ok.

I have a DNS service up and running. Normal resolving and loopback.
tested and ok.
Additionally I have configured /etc/hosts with all IP Adresses
(e.g. 192.168.1.160 romeo0.lan romeo0)

The full error message is:
"The hostname and canonical name for this host are not consistent when
checked from a Java process."



hostname
=> romeo0

hostname -f
=> romeo0.lan

host -v -t A romeo0.lan
=>

;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 37626
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL: 0

;; QUESTION SECTION:
;romeo0.lan. ** IN A

;; ANSWER SECTION:
romeo0.lan. 3600 IN A 192.168.1.160

;; AUTHORITY SECTION:
lan. 3600 IN NS romeo0.lan.


dig romeo0.lan

; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.17.**rc1.el6_4.4 <<>> romeo0.lan
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 61443
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL: 0

;; QUESTION SECTION:
;romeo0.lan. ** IN A

;; ANSWER SECTION:
romeo0.lan. 3600 IN A 192.168.1.160

;; AUTHORITY SECTION:
lan. 3600 IN NS romeo0.lan.

;; Query time: 0 msec
;; SERVER: 192.168.1.160#53(192.168.1.**160)

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