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Re: Problem getting DNS server list, no hostname set



2010/8/17 Moray Henderson <Moray Henderson ict-software org>:
> brem belguebli wrote:
>>Hi there,
>>
>>I may be addressing this to the wrong ML ?
>>
>>If so could someone point me to the right one ?
>>
>>Thanks
>>
>>Brem
>>
>>2010/8/13 brem belguebli <brem belguebli gmail com>:
>>> Hi,
>>>
>>> I started anaconda with log=debug to see if I get more information:
>>> The dns server option is really trapped but still the same message
>>> complaining it can't look up hostname.
>>>
>>> 09:40:13 DEBUG   : DHCPv4 eth0 - option routers default gateway 0:
>>> 192.168.84.254
>>> 09:40:13 DEBUG   : DHCPv4 eth0 - option domain-name-servers:
>>> 09:40:13 DEBUG   : DHCPv4 eth0 - domain-name-server 0: 10.146.0.11
>>> 09:40:13 DEBUG   : DHCPv4 eth0 - domain-name-server 1: 10.146.36.11
>>> 09:40:13 DEBUG   : DHCPv4 eth0 - option host-name: testVM
>>> 09:40:13 DEBUG   : nic_addr_send: add IFA_ADDRESS: 3
> 192.168.84.250/24
>>>
>>> 09:40:13 DEBUG   : nic_addr_send: add IFA_LOCAL: 3 192.168.84.250
>>>
>>> 09:40:13 DEBUG   : nic_addr_send: add address: 3 broadcast:
>>192.168.84.255
>>>
>>> 09:40:13 ERROR   : no DNS servers, can't look up hostname
>>>
>>> Any hint or idea ?
>>>
>>> Thanks
>>>
>>> 2010/8/12 brem belguebli <brem belguebli gmail com>:
>>>> Hi,
>>>>
>>>> I'm systematically hiting the message "no DNS servers, can't look up
>>>> hostname"  while trying to build a hostname based ks file VM
> install.
>>>>
>>>> The PXE server used  is a Rhel 5.4 X86_64, the DHCP service is
> offered
>>>> by dnsmasq.
>>>> The client is a VM expected to be installed with RHEL 5.4.
>>>>
>>>> When logging dsmasq, I can see that the dns server option (6) is
> sent
>>>> to the client  as well as the hostname option (12).
>>>>
>>>> Below the dnsmasq log on the server
>>>> Aug 12 13:24:16 cmxi1152 dnsmasq[11759]: DHCP packet: transaction-id
>>>> is 1664975136
>>>> Aug 12 13:24:16 cmxi1152 dnsmasq[11759]: Available DHCP range:
>>>> 192.168.84.250 -- 192.168.84.251
>>>> Aug 12 13:24:16 cmxi1152 dnsmasq[11759]: Vendor class: anaconda
>>>> Aug 12 13:24:16 cmxi1152 dnsmasq[11759]: DHCPREQUEST(br0)
>>>> 192.168.84.250 54:52:00:22:92:83
>>>> Aug 12 13:24:16 cmxi1152 dnsmasq[11759]: DHCPACK(br0) 192.168.84.250
>>>> 54:52:00:22:92:83 testVM
>>>> Aug 12 13:24:16 cmxi1152 dnsmasq[11759]: requested options:
> 1:netmask,
>>>> 28:broadcast, 3:router, 15:domain-name,
>>>> Aug 12 13:24:16 cmxi1152 dnsmasq[11759]: requested options:
>>>> 6:dns-server, 12:hostname, 33:static-route
>>>> Aug 12 13:24:16 cmxi1152 dnsmasq[11759]: next server: 192.168.84.254
>>>> Aug 12 13:24:16 cmxi1152 dnsmasq[11759]: bootfile name: pxelinux.0
>>>> Aug 12 13:24:16 cmxi1152 dnsmasq[11759]: tags: known
>>>> Aug 12 13:24:16 cmxi1152 dnsmasq[11759]: sent size:  1 option:
>>>> 53:message-type  05
>>>> Aug 12 13:24:16 cmxi1152 dnsmasq[11759]: sent size:  4 option:
>>>> 54:server-identifier  c0:a8:54:fe
>>>> Aug 12 13:24:16 cmxi1152 dnsmasq[11759]: sent size:  4 option:
>>>> 51:lease-time  00:00:1c:20
>>>> Aug 12 13:24:16 cmxi1152 dnsmasq[11759]: sent size:  4 option: 58:T1
>>>> 00:00:0e:10
>>>> Aug 12 13:24:16 cmxi1152 dnsmasq[11759]: sent size:  4 option: 59:T2
>>>> 00:00:18:9c
>>>> Aug 12 13:24:16 cmxi1152 dnsmasq[11759]: sent size:  4 option:
>>>> 1:netmask  ff:ff:ff:00
>>>> Aug 12 13:24:16 cmxi1152 dnsmasq[11759]: sent size:  4 option:
>>>> 28:broadcast  c0:a8:54:ff
>>>> Aug 12 13:24:16 cmxi1152 dnsmasq[11759]: sent size:  4 option:
>>>> 3:router  c0:a8:54:fe
>>>> Aug 12 13:24:16 cmxi1152 dnsmasq[11759]: sent size:  6 option:
>>>> 12:hostname  74:65:73:74:56:4d
>>>> Aug 12 13:24:16 cmxi1152 dnsmasq[11759]: sent size:  8 option:
>>>> 6:dns-server  0a:92:00:0b:0a:92:24:0b
>>>>
>>>> On client side (console ALT-F3 log)
>>>> 11:24:15 INFO     : getting kickstart file
>>>> 11:24:15 INFO     : sending dhcp request through device eth0
>>>> 11:24:15 INFO     : requesting dhcp timeout 45
>>>> 11:24:15 INFO     : Listening on LPF/eth0/54:52:00:22:93:83
>>>> 11:24:15 INFO     : Sending on LPF/eth0/54:52:00:22:93:83
>>>> 11:24:15 INFO     : Sending on Socket/fallback
>>>> 11:24:15 INFO     : DHCPDISCOVER on eth0 to 255.255.255.255 port 67
>>interval 5
>>>> 11:24:15 INFO     : DHCPOFFER from 192.168.84.254
>>>> 11:24:15 INFO     : DHCPREQUEST on eth0 to 255.255.255.255 port 67
>>>> 11:24:15 INFO     : DHCPACK from 192.168.84.254
>>>> 11:24:15 INFO     : bound to 192.168.84.250 -- renewal in 3052
> seconds.
>>>> 11:24:15 INFO     : DHCPv4 eth0 - obtained lease 192.168.84.250
>>>> 11:24:15 INFO     : DHCPv4 eth0 - option subnet-mask: 255.255.255.0
>>>> 11:24:15 INFO     : DHCPv4 eth0 - option subnet-mask - prefix_len:
> 24
>>>> broadcast: 192.168.84.254
>>>> 11:24:15 INFO     : DHCPv4 eth0 - option routers:
>>>> 11:24:15 ERROR : no DNS servers, can't look up hostname
>>>>
>>>> Thanks
>>>>
>>>> Brem
>
> Try booting from a CentOS 5.4 LiveCD (or image).  If that does not get a
> working DNS configuration through DHCP either, you will have a better
> environment for tracking it down.  I'd suspect either firewall or
> routing: if your VM really is getting 192.168.84.250 with default
> gateway 192.168.84.254, can that gateway talk to the DNS server at
> 10.146.0.11?

The VM is able to reach the DNS server, no firewall issue, the install
server NAT's all what is incoming from the VM to the outside.
I even did a tcpdump port 53 on the install server (that is also the
KVM host actually) to see if any DNS request is sent from the VM but
none.

> Is something on the way blocking the packets?  Or maybe the
> DNS server does not respond to requests from that subnet.

cf above and below, client is NATED, DNS server  answers the requests

>If you have
> access to the DNS server, check its logs, or run tcpdump to see if the
> requests are arriving.  "ip addr list" and "ip route list" will show
> your networking configuration, and should also work in the Anaconda
> shell window on Alt-F2.  "cat /etc/resolv.conf" shows DNS configuration,
> but I can't remember if that one works in Anaconda or not.
>
I'm not there yet , as I'm trying to build a per machine automated ks
environment, so no shell on Alt-F2 as stage2 is not loaded.
But when I cheat by entering the path to my ks file, I can get to the
shell and cat /etc/resolv.conf gives me the expected nameservers and
the expected domain entry , and I'm able then to request the DNS
server then to resolve my client hostname.
>
> Moray.
Thanks
> "To err is human.  To purr, feline"
>
Brem
>
>
>
>
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