Wednesday, June 24, 2015

domain name system - What would cause the hostname FQDN to repeat the suffix twice?

I have three new CentOS 6 servers that connect to a DHCP server to get an IP and to have DNS/rDNS setup to bind their FQDN and IP.




Two of them are behaving as expected.



One of them is appending the suffix twice.



Instead of fulton.mydomain.com we get fulton.mydomain.com.mydomain.com as the FQDN.



This is not coming from /etc/sysconfig/network:



[root@fulton ~]# cat /etc/sysconfig/network

NETWORKING=yes
HOSTNAME=fulton
[root@fulton ~]#


On the other two systems /etc/sysconfig/network also just has the single names.



This is acting as if the main name is "fulton.mydomain.com" which then has mydomain.com appended again.



I cannot figure out if machine "fulton" is reporting its name to DHCP as fulton.mydomain.com when it should be just using fulton or if something in the DHCP server is causing this.




I cannot find anywhere on fulton where the fulton.mydomain.com is specified instead of just fulton.



The /etc/hosts file on all machines is completely generic:



[root@fulton etc]# cat /etc/hosts
127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4
::1 localhost localhost.localdomain localhost6 localhost6.localdomain6



On the DHCP / DNS server system, the only mention of these systems is in:



/var/lib/named/dyn/mydomain.com.zone
/var/lib/named/dyn/10.0.zone


Thanks,
Laurence Brevard
San Jose, CA




Adding various hostname outputs and sysconfig/network



[root@fulton sysconfig]# hostname -v -f
gethostname()=`fulton.home.rcousins.com'
Resolving `fulton.home.rcousins.com' ...
Result: h_name=`fulton.home.rcousins.com.home.rcousins.com'
Result: h_addr_list=`10.0.5.223'
fulton.home.rcousins.com.home.rcousins.com



See above - OOPS



[root@fulton sysconfig]# hostname
fulton.home.rcousins.com


PRETTY SURE ABOVE SHOULD JUST BE: fulton



[root@fulton sysconfig]# hostname -s
fulton



SHORT NAME ABOVE IS CORRECT



[root@fulton sysconfig]# cat network /etc/sysconfig 
NETWORKING=yes
HOSTNAME=fulton


AND ABOVE IS CORRECT

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