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Thread: strange DNS issues, can resolve hostname but not IP and access some sites

  1. #1
    Join Date
    Dec 2019
    Beans
    5

    strange DNS issues, can resolve hostname but not IP and access some sites

    examples:

    ping hangs on IP address

    Code:
    moop@fightbiscuits:~/Downloads$ ping 8.8.8.8
    PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
    ^C
    --- 8.8.8.8 ping statistics ---
    6 packets transmitted, 0 received, 100% packet loss, time 5114ms
    but not on hostname

    Code:
    moop@fightbiscuits:~/Downloads$ ping google.com
    PING google.com(dfw25s27-in-x0e.1e100.net (2607:f8b0:4000:814::200e)) 56 data bytes
    64 bytes from dfw25s27-in-x0e.1e100.net (2607:f8b0:4000:814::200e): icmp_seq=1 ttl=55 time=24.4 ms
    64 bytes from dfw25s27-in-x0e.1e100.net (2607:f8b0:4000:814::200e): icmp_seq=2 ttl=55 time=23.0 ms
    64 bytes from dfw25s27-in-x0e.1e100.net (2607:f8b0:4000:814::200e): icmp_seq=3 ttl=55 time=18.2 ms
    ^C
    --- google.com ping statistics ---
    3 packets transmitted, 3 received, 0% packet loss, time 2002ms
    rtt min/avg/max/mdev = 18.233/21.900/24.410/2.651 ms
    can connect to ubuntu servers so updates work

    Code:
    moop@fightbiscuits:~/Downloads$ sudo apt-get update
    Get:1 file:/var/cuda-repo-10-0-local-10.0.130-410.48  InRelease
    Ign:1 file:/var/cuda-repo-10-0-local-10.0.130-410.48  InRelease
    Get:2 file:/var/cuda-repo-10-0-local-10.0.130-410.48  Release [574 B]
    Get:2 file:/var/cuda-repo-10-0-local-10.0.130-410.48  Release [574 B]
    Get:3 file:/var/cuda-repo-10-0-local-10.0.130-410.48  Release.gpg [833 B]
    Get:3 file:/var/cuda-repo-10-0-local-10.0.130-410.48  Release.gpg [833 B]
    Ign:3 file:/var/cuda-repo-10-0-local-10.0.130-410.48  Release.gpg
    Hit:4 https://deb.nodesource.com/node_13.x bionic InRelease
    Hit:5 http://us.archive.ubuntu.com/ubuntu bionic InRelease
    Hit:6 http://archive.canonical.com/ubuntu bionic InRelease
    It's almost as if it is random as to what sites it can access as I can curl and wget certain sites and not others.

    I don't know what to do. The conf files look ok. someone please walk me through the steps to troubleshoot this, I used to be pretty good at networking and linux but years of depression have robbed me of my skills and I'm trying to get back in the game!

  2. #2
    Join Date
    Mar 2010
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    Squidbilly-Land
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    18,809
    Distro
    Ubuntu Mate 16.04 Xenial Xerus

    Re: strange DNS issues, can resolve hostname but not IP and access some sites

    Looks like IPv6 networking is working, but not IPv4.
    Not all websites support IPv6. None of mine do. I don't have any IPv6 DNS records at all.

  3. #3
    Join Date
    Dec 2019
    Beans
    5

    Re: strange DNS issues, can resolve hostname but not IP and access some sites

    So how do i troubleshoot what to do to fix it?

  4. #4
    Join Date
    Aug 2005
    Location
    South Carolina, USA
    Beans
    25,021
    Distro
    Ubuntu 19.10 Eoan Ermine

    Re: strange DNS issues, can resolve hostname but not IP and access some sites

    Did your router issue an IPv6 address only and not IPv4? Check:
    Code:
    ip addr show
    You should see something like:

    Code:
    3: wlp3s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
        link/ether xx:c5:d4:0e:64:xx brd ff:ff:ff:ff:ff:ff
        inet 192.168.0.11/24 brd 192.168.0.255 scope global dynamic noprefixroute wlp3s0
           valid_lft 169902sec preferred_lft 169902sec
        inet6 2600:1700:5aa0:83c:b9cc:b20b:18f9:ba08/64 scope global temporary dynamic 
           valid_lft 601905sec preferred_lft 83395sec
        inet6 2600:1700:5aa0:83c:3c95:2494:87db:e8fa/64 scope global dynamic mngtmpaddr noprefixroute 
           valid_lft 2591796sec preferred_lft 604596sec
        inet6 fe80::3f3e:a058:dc6d:df91/64 scope link noprefixroute 
           valid_lft forever preferred_lft forever
    I suspect that you have inet6, that is IPv6, only. Please try rebooting the router.
    "Oh, Ubuntu, you are my favorite Linux-based operating system" --Dr. Sheldon Cooper, Ph.D., Sc.D.

  5. #5
    Join Date
    Dec 2019
    Beans
    5

    Re: strange DNS issues, can resolve hostname but not IP and access some sites

    Hmmm... wierd but I'll reboot the router when I'm done setting this other stuff up. Getting a virtual machine installed to run a gameserver. Thank you, would there be anything else I could try if that doesn't work?

    Code:
    moop@fightbiscuits:/etc/update-motd.d$ ip addr show
    1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000
        link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
        inet 127.0.0.1/8 scope host lo
           valid_lft forever preferred_lft forever
        inet6 ::1/128 scope host
           valid_lft forever preferred_lft forever
    2: eno1: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000
        link/ether b4:b5:2f:cf:75:42 brd ff:ff:ff:ff:ff:ff
        inet 192.168.0.44/24 brd 192.168.0.255 scope global dynamic noprefixroute eno1
           valid_lft 574122sec preferred_lft 574122sec
        inet6 2600:8807:5400:1321:c029:5c57:dd21:2021/64 scope global temporary dynamic
           valid_lft 86398sec preferred_lft 53469sec
        inet6 2600:8807:5400:1321::631a/128 scope global dynamic noprefixroute
           valid_lft 491092sec preferred_lft 491092sec
        inet6 2600:8807:5400:1321:c3d:4028:fa88:bb05/64 scope global temporary deprecated dynamic
           valid_lft 86398sec preferred_lft 0sec
        inet6 2600:8807:5400:1321:c0c6:e848:ebfe:bdb5/64 scope global dynamic mngtmpaddr noprefixroute
           valid_lft 86398sec preferred_lft 86398sec
        inet6 fe80::2a4c:110c:c7ef:6a0f/64 scope link noprefixroute
           valid_lft forever preferred_lft forever
    moop@fightbiscuits:/etc/update-motd.d$

  6. #6
    Join Date
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    South Carolina, USA
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    Ubuntu 19.10 Eoan Ermine

    Re: strange DNS issues, can resolve hostname but not IP and access some sites

    You certainly have an inet (IPv4) address. Can you ping the router?
    Code:
    ping -c3 192.168.0.1
    It may otherwise be 192.168.0.254.

    Any clues here?
    Code:
    traceroute -4 www.ubuntu.com
    "Oh, Ubuntu, you are my favorite Linux-based operating system" --Dr. Sheldon Cooper, Ph.D., Sc.D.

  7. #7
    Join Date
    Dec 2019
    Beans
    5

    Re: strange DNS issues, can resolve hostname but not IP and access some sites

    wI don't see anything odd with the router configuration but I'll delete the entry from it and reset now
    Code:
    moop@fightbiscuits:/$ traceroute -4 www.ubuntu.com
    traceroute to www.ubuntu.com (91.189.89.115), 30 hops max, 60 byte packets
     1  _gateway (192.168.0.1)  2.288 ms  3.645 ms  4.838 ms
     2  * * *
     3  * * *
     4  * * *
     5  * * *
     6  * * *
    (kept going to 30)
    moop@fightbiscuits:/$ ping -c3 192.168.0.1
    PING 192.168.0.1 (192.168.0.1) 56(84) bytes of data.
    64 bytes from 192.168.0.1: icmp_seq=1 ttl=64 time=2.22 ms
    64 bytes from 192.168.0.1: icmp_seq=2 ttl=64 time=1.62 ms
    64 bytes from 192.168.0.1: icmp_seq=3 ttl=64 time=2.09 ms
    
    --- 192.168.0.1 ping statistics ---
    3 packets transmitted, 3 received, 0% packet loss, time 2003ms
    rtt min/avg/max/mdev = 1.621/1.980/2.222/0.264 ms
    
    moop@fightbiscuits:/$
    omg I'm a moron. I'm sorry for wasting your time on such an obvious step. resetting the router worked.
    Last edited by moopthemighty; December 22nd, 2019 at 11:38 PM.

  8. #8
    Join Date
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    Ubuntu 19.10 Eoan Ermine

    Re: strange DNS issues, can resolve hostname but not IP and access some sites

    It doesn't appear that IPv4 traffic gets past the router. I agree that the problem may be in its configuration. Please check.
    "Oh, Ubuntu, you are my favorite Linux-based operating system" --Dr. Sheldon Cooper, Ph.D., Sc.D.

  9. #9
    Join Date
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    Re: strange DNS issues, can resolve hostname but not IP and access some sites

    Quote Originally Posted by moopthemighty View Post
    omg I'm a moron. I'm sorry for wasting your time on such an obvious step. resetting the router worked.
    We've all been there too. What you could do to help the community here is use the "thread tools" button near the top and mark this thread "SOLVED".

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