RHEL7 kickstart: how is hostname determined?
"Lee, David (LA Int,RAL,LSCI)" <[email protected]> Fri, 4 Oct 2019 08:22:23 +0000
| Newsgroups | gmane.linux.redhat.kickstart.general |
|---|---|
| Message-ID | <AM5PR01MB2929CB736680838BA997CF27BE9C0@AM5PR01MB2929.eurprd01.prod.exchangelabs.com> |
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All our hosts are registered in an Infoblox DHCP+DNS service as MAC+IP+host=
name. We have two one domains and one subdomain.
When we kickstart-install a new RHEL7 host on the main domain, it cleanly g=
ets its intended hostname from Infoblox/DNS. We can see this very early on=
by doing an Alt-F2 and querying the hostname. All is well.
But on the subdomain it gets the name "localhost.localdomain" (which seems =
to be the "in the absence of anything else" default).
A wireshark trace of installations shows a DHCP request and ack. On the ma=
in domain this is quickly followed by a DNS PTR query from the host, giving=
the host's IP address and successfully returning the host's hostname. By =
contrast, on the subdomain, this query is never initiated. (On both domain=
s, there are subsequent successful DNS queries of other things as part of t=
he ensuing installation, demonstrating that DNS activity is happening.)
What might be triggering the hosts on the two different domains to behave d=
ifferently, that is, send or not send that DNS/PTR query?
Looking deeper into that preceding DHCP request/ACK: The main domain, wher=
e all works well, is (for example) "company.org". The subdomain (where thi=
s lack of hostname issue arises) is a subdomain, e.g. "sub.company.org". O=
ne oddity I spotted, is that the DHCP/ACK returns the same "domain-name" op=
tion-15 "company.org" for both. I wonder if that is precipitating a subseq=
uent problematical behaviour in that "sub.company.org" context?
Any thoughts? Thanks.
-- David Lee
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nts are free from viruses and we cannot accept liability for any damage whi=
ch you may sustain as a result of software viruses which may be transmitted=
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nd Wales with its registered office at Diamond House, Harwell Science and I=
nnovation Campus, Didcot, Oxfordshire, OX11 0DE, United Kingdom
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<body dir=3D"ltr">
<div style=3D"font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12p=
t; color:rgb(0,0,0)">
All our hosts are registered in an Infoblox DHCP+DNS service as MAC+=
;IP+hostname. We have two one domains and one subdomain.<br>
</div>
<div style=3D"font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12p=
t; color:rgb(0,0,0)">
</div>
<div style=3D"font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12p=
t; color:rgb(0,0,0)">
<br>
</div>
<div style=3D"font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12p=
t; color:rgb(0,0,0)">
When we kickstart-install a new RHEL7 host on the main domain, it cleanly g=
ets its intended hostname from Infoblox/DNS. We can see this very ear=
ly on by doing an Alt-F2 and querying the hostname. All is well.<br>
</div>
<div style=3D"font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12p=
t; color:rgb(0,0,0)">
<br>
</div>
<div style=3D"font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12p=
t; color:rgb(0,0,0)">
But on the subdomain it gets the name "localhost.localdomain" (wh=
ich seems to be the "in the absence of anything else" default).</=
div>
<div style=3D"font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12p=
t; color:rgb(0,0,0)">
<br>
</div>
<div style=3D"font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12p=
t; color:rgb(0,0,0)">
A wireshark trace of installations shows a DHCP request and ack. On t=
he main domain this is quickly followed by a DNS PTR query from the host, g=
iving the host's IP address and successfully returning the host's hostname.=
By contrast, on the subdomain, this
query is never initiated. (On both domains, there are subsequent suc=
cessful DNS queries of other things as part of the ensuing installation, de=
monstrating that DNS activity is happening.)</div>
<div style=3D"font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12p=
t; color:rgb(0,0,0)">
<br>
</div>
<div style=3D"font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12p=
t; color:rgb(0,0,0)">
What might be triggering the hosts on the two different domains to behave d=
ifferently, that is, send or not send that DNS/PTR query?</div>
<div style=3D"font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12p=
t; color:rgb(0,0,0)">
<br>
</div>
<div style=3D"font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12p=
t; color:rgb(0,0,0)">
Looking deeper into that preceding DHCP request/ACK: The main domain,=
where all works well, is (for example) "company.org". The =
subdomain (where this lack of hostname issue arises) is a subdomain, e.g. &=
quot;sub.company.org". One oddity I spotted, is that the
DHCP/ACK returns the same "domain-name" option-15 "company.=
org" for both. I wonder if that is precipitating a subsequent pr=
oblematical behaviour in that "sub.company.org" context?</div>
<div style=3D"font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12p=
t; color:rgb(0,0,0)">
<br>
</div>
<div style=3D"font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12p=
t; color:rgb(0,0,0)">
Any thoughts? Thanks.</div>
<div style=3D"font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12p=
t; color:rgb(0,0,0)">
<br>
</div>
<div style=3D"font-family:Calibri,Arial,Helvetica,sans-serif; font-size:12p=
t; color:rgb(0,0,0)">
-- David Lee<br>
</div>
<p align=3D"justify"> </p>
<p align=3D"justify">-- </p>
<p align=3D"justify">This e-mail and any attachments may contain confidenti=
al, copyright and or privileged material, and are for the use of the intend=
ed addressee only. If you are not the intended addressee or an authorised r=
ecipient of the addressee please notify us of receipt by returning the e-ma=
il and do not use, copy, retain, distribute or disclose the information in =
or attached to the e-mail.<br />Any opinions expressed within this e-mail a=
re those of the individual and not necessarily of Diamond Light Source Ltd.=
<br />Diamond Light Source Ltd. cannot guarantee that this e-mail or any a=
ttachments are free from viruses and we cannot accept liability for any dam=
age which you may sustain as a result of software viruses which may be tran=
smitted in or with the message.<br />Diamond Light Source Limited (company =
no. 4375679). Registered in England and Wales with its registered office at=
Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire,=
OX11 0DE, United Kingdom<br /> </p></body>
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