Rob
DNS service for my clients is provided by my gateway server, the same
machine as the DHCPD server. I think that's what the "option
domain-name-servers" line does. This allows me to provide 192.168
addresses to them when they try to access anything inside the house
with a name. If it's not a locally defined name, BIND forwards the
request to the internet.
I'm not sure I understand about dhcpd log and dns log. I scan
/var/log/messages, using the service name as the key. Looking at
'named' entries, all I see are messages of the form
"clients-per-query increased to XX".
I'm still mystified by the fact that only the i-devices (iphone,
ipad) exhibit this behavior of rapid dhcpd renewals. Mac's and PC's don't.
David
At 06:48 AM 2/17/2016, you wrote:
>On 16/02/16 16:59, david wrote:
>>Folks
>>
>>This might be the wrong place to ask, but I don't know where to turn.
>>My internal home network, including wireless, is controlled by a
>>Centos6 server, which provides dhcpd services, along with NAT. I
>>have DHCPD configured with the addresses 192.168.155.200 through
>>192.168.155.254 as the range for dynamic allocations. The
>>default-lease time is 1800 seconds, the maximum is 3600 seconds.
>>
>>My windows clients, and even an ipad-mini behave nicely, asking for
>>DHCP renewals once ever five minutes, or at about 80% of the
>>default lease time, a behavior I can understand. However, several
>>of my guests, with their own iPads, I-watches, iPhones, connect to
>>my network (via a wireless access point which does not do routing
>>functions) and they're renewing once every 20-30 seconds. In
>>addition, these devices also loose connectivity for brief
>>intervals, which seems to be roughly synchronized with dhcp
>>renewal. This last fact I deduce by doing "tail -f
>>/etc/log/messages" and hearing them say "lost connection" at just
>>about the same moment the DHCPREQUEST and DHCPACK statements show up.
>>
>>It's difficult to believe that Apple IOS devices (all of which are
>>running apple's latest) have a dhcp client problem not shared by
>>windows or even linux hosts.
>>
>>Does anyone have any clues?
>does your dhcpd update the dns? name resolution for devices seems to
>be required for some applications and thus the dns needs to know
>about the leases. Have you checked your dhcpd log entries and your
>dns log entries? I have had situations where the dhcpd lease is
>dropped due to not being able to complete dns update of the info -
>thus the client retries again and again - they do get onto the
>internet but the connection drops and a new lease is requested,
>HTH
>>David Kurn
>>San Francisco
>>
>>DHCPD.CONF file is excerpted below:
>>
>>----------------------------------------
>>ddns-update-style none;
>>
>>subnet 192.168.155.0 netmask 255.255.255.0 {
>> authoritative;
>> option routers 192.168.155.2;
>> option subnet-mask 255.255.255.0;
>> option broadcast-address 192.168.155.255;
>> option domain-name "daku.org";
>> option domain-name-servers 192.168.155.2;
>> option netbios-name-servers 192.168.155.2;
>>
>> option time-offset -28800; # Pacific standard time
>>
>> range dynamic-bootp 192.168.155.200 192.168.155.254;
>> default-lease-time 1800;
>> max-lease-time 3600;
>>}
>>
>>--------------------------------------------