[opensuse] How to Clear Local Nameserver Cache when other LAN IPs change?
All, This seems like it should be something that I know of the top of my head, but I must not. On leap 15.0 on my laptop, I had updated a few other boxes on the LAN. (over ssh) Upon reboot the IP for the host I had updated changed local server on LAN running ISC dhcpd and bind. (I'm not sure what prompted the change, but it seems like something Linux 5.6.5 related in the way the DHCID TXT string is calculated by the client based on the MAC? - that's for another day) The updated host and server were both happy with what the new IP was for the updated hosts (simple nslookup confirmed that), but my Leap 15.0 laptop still had the old IP cached somewhere (nscd?) and was unable to reconnect to the remote updated hosts after they were rebooted (I could connect with ssh -Y NEWIP just fine) So the problem was my laptop still holding the old IPs in cache somewhere. What do I restart or how can I flush the cache so my laptop has the new IP for the client so name resolution works from my laptop? (restart nscd?, some nsswitch command? -- that's where I got stuck) I don't have any other caching daemon running other than what Leap starts by default. So what is the magic utility I need? (RTFM answers are fine as long as which 'M' is identified `:)` -- David C. Rankin, J.D.,P.E. -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org
David C. Rankin wrote:
The updated host and server were both happy with what the new IP was for the updated hosts (simple nslookup confirmed that), but my Leap 15.0 laptop still had the old IP cached somewhere (nscd?) and was unable to reconnect to the remote updated hosts after they were rebooted (I could connect with ssh -Y NEWIP just fine)
So the problem was my laptop still holding the old IPs in cache somewhere.
That would be nscd.
What do I restart or how can I flush the cache so my laptop has the new IP for the client so name resolution works from my laptop?
nscd -i hosts or just restart nscd. -- Per Jessen, Zürich (14.0°C) http://www.cloudsuisse.com/ - your owncloud, hosted in Switzerland. -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org
David C. Rankin wrote:
The updated host and server were both happy with what the new IP was for the updated hosts (simple nslookup confirmed that), but my Leap 15.0 laptop still had the old IP cached somewhere (nscd?) and was unable to reconnect to the remote updated hosts after they were rebooted (I could connect with ssh -Y NEWIP just fine)
So the problem was my laptop still holding the old IPs in cache somewhere.
That would be nscd.
What do I restart or how can I flush the cache so my laptop has the new IP for the client so name resolution works from my laptop?
nscd -i hosts or just restart nscd. Thank you Per, that is what looked logical -- though having never played with nscd I glad I checked. The underlying issue is what changed in the 5.6.5 kernel that causes hosts to recalculate their TXT record has so that the next dhcpd update to DNS issues an address but complains the address TXT records are "not mine." -- oh well, I'll stumble through that one tomorrow. -- Per Jessen, Zürich (14.0°C) http://www.cloudsuisse.com/ - your owncloud, hosted in Switzerland. -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org
David C. Rankin wrote:
Thank you Per, that is what looked logical -- though having never played with nscd I glad I checked.
The underlying issue is what changed in the 5.6.5 kernel that causes hosts to recalculate their TXT record has so that the next dhcpd update to DNS issues an address but complains the address TXT records are "not mine." -- oh well, I'll stumble through that one tomorrow.
Doesn't sound like a kernel issue. I heard something like that a couple of weeks ago, but it was a DHCP issue, something to do with an ID that changed. Sorry for being so vague. In my case it only caused a system to be issued two dynamic addresses (there's an open bugreport on that). -- Per Jessen, Zürich (14.2°C) http://www.cloudsuisse.com/ - your owncloud, hosted in Switzerland. -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org
Hello, Hello, In the Message; Subject : [opensuse] How to Clear Local Nameserver Cache when other LAN IPs change? Message-ID : <e81abf11-329b-bb19-9b71-1cdcfaf42847@suddenlinkmail.com> Date & Time: Mon, 20 Apr 2020 03:31:46 -0500 [DCR] == "David C. Rankin" <drankinatty@suddenlinkmail.com> has written: DCR> This seems like it should be something that I know of the top of my head, DCR> but I must not. On leap 15.0 on my laptop, I had updated a few DCR> other boxes on the LAN. (over ssh) Upon reboot the IP for the DCR> host I had updated changed local server on LAN running ISC dhcpd DCR> and bind. (I'm not sure what prompted the change, but it seems DCR> like something Linux 5.6.5 related in the way the DHCID TXT DCR> string is calculated by the client based on the MAC? - that's DCR> for another day) [...] DCR> So the problem was my laptop still holding the old IPs in DCR> cache somewhere. What do I restart or how can I flush the cache DCR> so my laptop has the new IP for the client so name resolution DCR> works from my laptop? (restart nscd?, some nsswitch command? -- DCR> that's where I got stuck) I don't have any other caching daemon DCR> running other than what Leap starts by default. So what is the DCR> magic utility I need? No, not a cache issue, and no utility. You have to shorten the TTL value in the the zone file, at a moment. Please have a look; https://www.liquidweb.com/kb/how-to-lowering-your-dns-ttls/ Refards, --- ┏━━┓彡 Masaru Nomiya mail-to: nomiya @ galaxy.dti.ne.jp ┃＼／彡 ┗━━┛ Think. -- The IBM slogan -- -- To unsubscribe, e-mail: opensuse+unsubscribe@opensuse.org To contact the owner, e-mail: opensuse+owner@opensuse.org
participants (3)
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David C. Rankin -
Masaru Nomiya -
Per Jessen