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Destination net unreachable when pinging

By Joel amos
Jun 30, 2015
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  1. Whenever I ping my university's website, emu.edu, I get the message: "Destination net unreachable." This only happens for all subdirectories and subdomains of emu.edu. I am able to visit the main website via my web browser, but problems arise when I try to connect to vpn.emu.edu via Cisco AnyConnect Secure Mobility Client, which allows me to connect to my school's network.

    Three days ago, my school added a second ISP to double the school's bandwidth. Could this be in any way related? Because four days ago, I was able to connect to the VPN. The result from Isitdownrightnow would suggest that the problem is my own. But then, how does one explain being able to connect well to other sites?
     
  2. jobeard

    jobeard TS Ambassador Posts: 9,322   +622

    The message means what it says - - there is no path to the address given to ping. You can see for yourself with this test:

    get a command prompt and enter
    • first find your pc address on the lan with IPCONFIG
    • (mine shows up as: IPv4 Address. . . : 192.168.0.5)
    • now PING the device at x.x.x.253
    • in my case PING 192.168.0.253
    you get
    Code:
    ping 192.168.0.253
    Pinging 192.168.0.253 with 32 bytes of data:
    Reply from 192.168.0.5: Destination host unreachable.
    Reply from 192.168.0.5: Destination host unreachable.
    
    Let's say you're trying to ping the system webserver.emu.edu but it is behind a firewall. The firewall allows port 80 so browsing works.
    The path for ping looks like
    • yourPC - - EMU.firewall -- webserver
    Ping gets to the firewall, but does not move thru it and thus you get your Dest Not Reachable.

    Why? Because PING is not port related (like port 80 ->webservers) but rather is a protocol.
     
  3. Joel amos

    Joel amos TS Rookie Topic Starter

    I'm a little confused; how is emu.edu different than any other website?
     
  4. jobeard

    jobeard TS Ambassador Posts: 9,322   +622

    It is not, but fail to understand that PING is not required to respond for any website. If it does, nice, but the test is using the browser itself
     
  5. Joel amos

    Joel amos TS Rookie Topic Starter

    Well, I have tested vpn.emu.edu is the browser, and I am not able to connect. I thought the error message that I am getting when pinging would be related.
     
  6. jobeard

    jobeard TS Ambassador Posts: 9,322   +622

    VPN - - By that name, I would never expect ping to respond, as that (I would assume) would be the VPN server and it would respond on a secured port.

    Have you ever been able to access the VPN or the website (usually they are public and not on a vpn server).
     
  7. Joel amos

    Joel amos TS Rookie Topic Starter

    Yes, as per my post, I was able to just four days ago.
     
  8. jobeard

    jobeard TS Ambassador Posts: 9,322   +622

    Whois emu.edu
    Code:
    Domain Name: EMU.EDU
    
    Registrant:
      Eastern Mennonite University
      1200 Park Road
      Harrisonburg, VA 22801-2462
      UNITED STATES
    
    Name Servers:
      INSERV1.EMU.EDU  199.111.20.10
      INSERV2.EMU.EDU  199.111.20.12
    
    nslookup emu.edu
    Code:
    $ nslookup emu.edu
    Non-authoritative answer:
    Server:  dns-cac-lb-01.rr.com
    Address:  209.18.47.61
    
    Name:  emu.edu
    Address:  199.111.20.20
    
    nslookup vpn.emu.edu
    Code:
    Non-authoritative answer:
    Server:  dns-cac-lb-01.rr.com
    Address:  209.18.47.61
    
    Name:  vpn.emu.edu
    Address:  199.111.20.110
    
    ping either {vpn.}emu.edu
    >> TIMEOUT

    Tracert emu.edu
    Code:
    Tracing route to emu.edu [199.111.20.20]
    over a maximum of 30 hops:
    
      1  <1 ms  <1 ms  <1 ms  localrouter [192.168.0.1]
      2  10 ms  8 ms  8 ms  cpe-75-85-0-1.socal.res.rr.com [75.85.0.1]
      3  9 ms  11 ms  9 ms  tge0-9-0-23.wlvgcabn02h.socal.rr.com [24.30.172.141]
      4  13 ms  11 ms  15 ms  agg22.vnnycajz02r.socal.rr.com [72.129.14.168]
      5  14 ms  10 ms  15 ms  agg29.tustcaft01r.socal.rr.com [72.129.13.2]
      6  14 ms  14 ms  23 ms  bu-ether16.tustca4200w-bcr00.tbone.rr.com [66.109.6.64]
      7  11 ms  11 ms  12 ms  0.ae2.pr1.lax10.tbone.rr.com [107.14.19.54]
      8  13 ms  15 ms  14 ms  las-b21-link.telia.net [62.115.36.57]
      9  52 ms  50 ms  49 ms  dls-b21-link.telia.net [80.91.254.170]
     10  70 ms  79 ms  69 ms  atl-bb1-link.telia.net [80.91.254.164]
     11  68 ms  69 ms  69 ms  shentel-ic-307320-atl-bb1.c.telia.net [80.239.194.106]
     12  *  *  *  Request timed out.
     13  90 ms  91 ms  89 ms  204.111.0.190 <<<<
     14  *  *  *  Request timed out.
     15  *  *  *  Request timed out.
     16  *  *  *  Request timed out.
     17  *  *  *  Request timed out.
    
    204.111.0.190 =>
    OrgName: Shentel Service Company
    OrgId: SHENTE
    Address: 124 South Main Street
    City: Edinburg
    StateProv: VA​
    looks like an ISP
     
  9. Joel amos

    Joel amos TS Rookie Topic Starter

    So does this indicate that it is not a problem with my connection?
     
  10. jobeard

    jobeard TS Ambassador Posts: 9,322   +622

    Yes - - at least from Los Angeles, the path to emu.edu is broken.

    you can test for yourself, from your location, by getting a command prompt and entering
    tracert emu.edu
    the last response should be the ip-address thereof, aka 199.111.20.20
     
  11. Joel amos

    Joel amos TS Rookie Topic Starter

    Yes, it is broken. Why am I able to connect to the site via a web browser?

    Also, Shentel is the new ISP that the school just added.
     
    Last edited: Jul 1, 2015
  12. jobeard

    jobeard TS Ambassador Posts: 9,322   +622

    Investigating DNS:::
    Code:
    $ nslookup emu.edu 8.8.8.8
    Non-authoritative answer:
    Server:  google-public-dns-a.google.com
    Address:  8.8.8.8
    Name:  emu.edu
    Address:  199.111.20.20
    
    $ nslookup www.emu.edu 8.8.8.8
    Non-authoritative answer:
    Server:  google-public-dns-a.google.com
    Address:  8.8.8.8
    Name:  www.emu.edu
    Address:  199.111.20.20
    
    $ nslookup vpn.emu.edu 8.8.8.8
    Non-authoritative answer:
    Server:  google-public-dns-a.google.com
    Address:  8.8.8.8
    Name:  vpn.emu.edu
    Address:  199.111.20.110
    
    So the first two urls map to the same server while the vpn is isolated.

    I too can reach www.emu.edu with my browser and yet tracert says the path is broken (btw tracert uses ping to perform its function).
    IMO, this demonstrates a comment earlier that a website is not required to respond to ping.

    1. in all cases, regardless of the target being tested, ping fails for {,vpn,www}.emu.edu
    2. yet http (port 80) can access the website
    Your issue lay between the new ISP and the VPN server. I would guess the ISP has not setup the firewall for the vpn traffic.
     
    Last edited: Aug 23, 2015
  13. Joel amos

    Joel amos TS Rookie Topic Starter

    Thanks for the help!
     

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