DNS - Slow Resolve Issue



  • Hey All,

    Odd issue happening and would love some help on where to start troubleshooting.  I'm getting very slow response times for DNS lookups (browsing to google.com, etc.).  I can fix this when I reboot pfSense and all works fine for about 5 minutes, then the same issues starts happening again.  DNS is set to my local DNS server, however I ruled that out as the issue as it's the same problem if I originate from that machine.

    Also the other odd thing is that if I change my DNS to 8.8.8.8 everything seems to work fine again.  This seems like an issue/setting with pfSense due to the fact that when I reboot the box it works just fine using my internal DNS for about 5 minutes, then it slows way down again.

    Anyone have an idea?

    Cheers,
    Miscue.



  • Also to add:

    • WAN connection is fine - good up/down speeds.
    • Internet becomes sluggish when trying to brows from behind pfSense.  This is after there DNS slowness appears as well.


  • Added some Firewall blocking logs I'm seeing.  Not sure if they are related.

    ![Screen Shot 2015-07-27 at 3.32.50 PM.png](/public/imported_attachments/1/Screen Shot 2015-07-27 at 3.32.50 PM.png)
    ![Screen Shot 2015-07-27 at 3.32.50 PM.png_thumb](/public/imported_attachments/1/Screen Shot 2015-07-27 at 3.32.50 PM.png_thumb)



  • I don't think it's the above firewall issues.  Another important update that I found while searching the forums.  I'm using PPPOE for the WAN connection (DSL modem in bridge mode on the other end).  If I disconnect/reconnect that interface (Gets another IP address) the connection works fine again.

    Symptoms come back after about 5 minutes again …


  • Rebel Alliance Global Moderator

    So you have pfsense using what for its own dns?  And where do your clients point to pfsense or your some other dns?  Is this a forwarder or a resolver?

    Clearly those are just out of state, but pfsense can not resolve them via ptr.. which I would hope your own local IP 172.16.10.105 should have a ptr..  What is your dhcp pfsense or something else?  That 17.110 does not resolve but its owned by apple

    ;; QUESTION SECTION:
    ;218.229.119.17.in-addr.arpa.  IN      PTR

    ;; AUTHORITY SECTION:
    17.in-addr.arpa.        7200    IN      SOA    gridmaster-ib.apple.com. hostmaster.apple.com. 2010092746 1800 900 2592000 7200