Dnsmasq missing default parameter: min-cache-ttl

Discussion in 'Tomato Firmware' started by rs232, Feb 13, 2019.

  1. rs232

    rs232 Network Guru Member

    Running Freshtomato 2019.5 beta

    This morning I found my router unresponsive. Rebooted and checked the logs. Found plenty of references to something like this:

    Code:
    Feb 13 08:45:39 tomato36k daemon.warn dnsmasq[26256]: Maximum number of concurrent DNS queries reached (max: 500)
    Feb 13 08:46:07 tomato36k daemon.warn dnsmasq[26256]: Maximum number of concurrent DNS queries reached (max: 500)
    Feb 13 08:46:29 tomato36k daemon.warn dnsmasq[26256]: Maximum number of concurrent DNS queries reached (max: 500)
    Feb 13 08:47:24 tomato36k daemon.warn dnsmasq[26256]: Maximum number of concurrent DNS queries reached (max: 500)
    Feb 13 08:47:41 tomato36k daemon.warn dnsmasq[26256]: Maximum number of concurrent DNS queries reached (max: 500)
    Feb 13 08:47:56 tomato36k daemon.warn dnsmasq[26256]: Maximum number of concurrent DNS queries reached (max: 500)
    Feb 13 08:48:20 tomato36k daemon.warn dnsmasq[26256]: Maximum number of concurrent DNS queries reached (max: 500)
    Feb 13 08:48:38 tomato36k daemon.warn dnsmasq[26256]: Maximum number of concurrent DNS queries reached (max: 500)
    Feb 13 08:48:53 tomato36k daemon.warn dnsmasq[26256]: Maximum number of concurrent DNS queries reached (max: 500)
    Feb 13 08:49:10 tomato36k daemon.warn dnsmasq[26256]: Maximum number of concurrent DNS queries reached (max: 500)
    Feb 13 08:49:22 tomato36k daemon.warn dnsmasq[26256]: Maximum number of concurrent DNS queries reached (max: 500)
    Feb 13 08:49:35 tomato36k daemon.warn dnsmasq[26256]: Maximum number of concurrent DNS queries reached (max: 500)
    Feb 13 08:51:14 tomato36k daemon.warn dnsmasq[26256]: Maximum number of concurrent DNS queries reached (max: 500)
    Feb 13 08:51:40 tomato36k daemon.warn dnsmasq[26256]: Maximum number of concurrent DNS queries reached (max: 500)
    Feb 13 08:54:12 tomato36k daemon.warn dnsmasq[26256]: Maximum number of concurrent DNS queries reached (max: 500)
    Feb 13 08:57:36 tomato36k daemon.warn dnsmasq[26256]: Maximum number of concurrent DNS queries reached (max: 500)
    Feb 13 08:59:36 tomato36k daemon.warn dnsmasq[26256]: Maximum number of concurrent DNS queries reached (max: 500)
    I am not sure this is 100% related but there was no particular network activity at that point of time apart from some torrenting and a tor browser open.

    After hitting the search button on google I have found this interesting article:
    https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=736362

    It appears like it's a good idea to add this parameter as the default to prevent problem with miconfigured DNS records in Internet:

    Code:
    min-cache-ttl=60
     
    pedro311 likes this.
  2. rgnldo

    rgnldo Networkin' Nut Member

    A suggestion:
    Code:
    local-ttl=600
    server=/pool.ntp.org/1.1.1.1
     
  3. rgnldo

    rgnldo Networkin' Nut Member

    adjusted.
    http://www.thekelleys.org.uk/dnsmasq/CHANGELOG
    I do not recommend using TTL by default. Routing or caching varies from network to network. Dnsmasq is very sensitive to these settings. The less interference, the better. Each user makes their need.
     
  4. rs232

    rs232 Network Guru Member

    I just wanted to give an update on this topic as it all started with the annoying error message.

    Maximum number of concurrent DNS queries reached (max: 500)

    error of mine. It *might* be something stupid I did. This happens on two devices living on different physical location but connected via tinc. Wht it's strange is that it happend on both of them. They both run Stubby but for what I thought it was resilience I also added the each other server=x.x.x.x directive into dnsmasq (in case the local stubby fails). So if I understood this right now I instead created a query loop as dnsmasq load balances queries, so there will be a situation where the dnsmasq on one router send query to each other and way back.

    So bottom line, I agree, no need to modify the default min-cache-ttl. I hope others can learn from my mistakes :)
     
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