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Hi folks, My FC3 workstation is connected 1o 1.5Mb broadband via ADSL modem to telephone line and with dynamic IP allotted on connection. I have been suffering on slow Internet ...
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  1. #1
    Linux Guru
    Join Date
    Sep 2004
    Posts
    1,792

    Networking question


    Hi folks,

    My FC3 workstation is connected 1o 1.5Mb broadband via ADSL modem to telephone line and with dynamic IP allotted on connection.

    I have been suffering on slow Internet browsing for a week on acount of dead primary nameserver which was found later. Each time after connecting ISP server a set of nameservers was allotted, namely the primary and secondary nameservers. They were seldomly changed, almost the same set each time on connection. The ISP disputed my finding saying the primary nameserver was alive pinged on his Windows PC. Finally the ISP changed another new set of nameservers. But the new primary nameserver assigned still died.

    New set of nameservers;
    # cat /etc/resolv.conf
    nameserver 203.123.77.196 (Primary)
    nameserver 202.123.77.213 (Secondary)


    The history of ping and traceroute are as follows;

    ping command
    ============
    1)
    Tested on FC3
    # ping -c 3 202.123.77.196
    Code:
    PING 202.123.77.196 (202.123.77.196) 56(84) bytes of data.
    From 202.123.95.82 icmp_seq=0 Time to live exceeded
    From 202.123.95.82 icmp_seq=1 Time to live exceeded
    From 202.123.95.82 icmp_seq=2 Time to live exceeded
    
    --- 202.123.77.196 ping statistics ---
    3 packets transmitted, 0 received, +3 errors, 100% packet loss, time 2002ms, pipe 2
    It indicated 100% packet loss.


    2)
    Tested on WinME
    C:\WINDOWS>ping -n 3 202.123.77.196
    Code:
    Pinging 202.123.77.196 with 32 bytes of data:
    
    Reply from 202.123.95.82: TTL expired in transit.
    Reply from 202.123.95.82: TTL expired in transit.
    Reply from 202.123.95.82: TTL expired in transit.
    
    Ping statistics for 202.123.77.196:
        Packets: Sent = 3, Received = 3, Lost = 0 (0% l
    Approximate round trip times in milli-seconds:
    From the abve it indicates 0% packet loss. Now I'm not surprised why the ISP claimed no problem on the nameservers pinged on his Windows PC. Windows allowed the feedback from another nameserver getting through and indicating 0% packet loss. I suppose this was the security problem. If I'm wrong please correct me. Tks.


    3)
    Tested on FC3
    # ping -c 3 202.123.77.213
    Code:
    PING 202.123.77.213 (202.123.77.213) 56(84) bytes of data.
    64 bytes from 202.123.77.213: icmp_seq=0 ttl=252 time=37.3 ms
    64 bytes from 202.123.77.213: icmp_seq=1 ttl=252 time=18.7 ms
    64 bytes from 202.123.77.213: icmp_seq=2 ttl=252 time=18.9 ms
    
    --- 202.123.77.213 ping statistics ---
    3 packets transmitted, 3 received, 0% packet loss, time 2002ms
    rtt min/avg/max/mdev = 18.729/25.001/37.335/8.723 ms, pipe 2
    No packet loss found.



    traceroute
    ==========

    1)
    Tested on FC3
    # traceroute 202.123.77.196
    Code:
    traceroute to 202.123.77.196 (202.123.77.196), 30 hops max, 38 byte packets
     1  203.88.164.1 (203.88.164.1)  34.436 ms  18.725 ms  17.194 ms
     2  202-123-94-73.ihenderson.com (202.123.94.73)  31.701 ms  17.349 ms  17.180 ms
     3  202-123-94-51.ihenderson.com (202.123.94.51)  33.842 ms  16.773 ms  17.193 ms
     4  202-123-95-82.ihenderson.com (202.123.95.82)  29.837 ms  17.027 ms  17.181 ms
     5  hdc-coreB-fe110.ihenderson.com (202.123.95.81)  33.179 ms  16.775 ms  17.461 ms
     6  202-123-95-82.ihenderson.com (202.123.95.82)  28.888 ms  23.199 ms  17.346 ms
     7  hdc-coreB-fe110.ihenderson.com (202.123.95.81)  32.042 ms  18.007 ms  17.933 ms
     8  202-123-95-82.ihenderson.com (202.123.95.82)  34.393 ms  18.015 ms  16.936 ms
     9  hdc-coreB-fe110.ihenderson.com (202.123.95.81)  25.559 ms  17.237 ms  17.462 ms
    10  202-123-95-82.ihenderson.com (202.123.95.82)  37.132 ms  18.018 ms  17.452 ms
    11  hdc-coreB-fe110.ihenderson.com (202.123.95.81)  38.051 ms  17.523 ms  17.176 ms
    12  202-123-95-82.ihenderson.com (202.123.95.82)  36.670 ms  17.502 ms  17.194 ms
    13  hdc-coreB-fe110.ihenderson.com (202.123.95.81)  35.245 ms  17.743 ms  17.465 ms
    14  202-123-95-82.ihenderson.com (202.123.95.82)  33.834 ms  17.497 ms  17.192 ms
    15  hdc-coreB-fe110.ihenderson.com (202.123.95.81)  31.714 ms  17.290 ms  17.175 ms
    16  202-123-95-82.ihenderson.com (202.123.95.82)  29.592 ms  17.966 ms  17.934 ms
    17  hdc-coreB-fe110.ihenderson.com (202.123.95.81)  36.741 ms  19.286 ms  17.399 ms
    18  202-123-95-82.ihenderson.com (202.123.95.82)  33.879 ms  17.482 ms  17.181 ms
    19  hdc-coreB-fe110.ihenderson.com (202.123.95.81)  30.061 ms  17.550 ms  17.451 ms
    20  202-123-95-82.ihenderson.com (202.123.95.82)  33.983 ms  17.933 ms  17.698 ms
    21  hdc-coreB-fe110.ihenderson.com (202.123.95.81)  27.707 ms  17.477 ms  16.965 ms
    22  202-123-95-82.ihenderson.com (202.123.95.82)  32.793 ms  17.480 ms  17.446 ms
    23  hdc-coreB-fe110.ihenderson.com (202.123.95.81)  36.703 ms  17.719 ms  17.952 ms
    24  202-123-95-82.ihenderson.com (202.123.95.82)  30.638 ms  17.701 ms  18.198 ms
    25  hdc-coreB-fe110.ihenderson.com (202.123.95.81)  34.904 ms  18.215 ms  18.188 ms
    26  202-123-95-82.ihenderson.com (202.123.95.82)  29.862 ms  17.978 ms  16.940 ms
    27  hdc-coreB-fe110.ihenderson.com (202.123.95.81)  23.821 ms  17.564 ms  18.855 ms
    28  202-123-95-82.ihenderson.com (202.123.95.82)  36.947 ms  17.711 ms  17.946 ms
    29  hdc-coreB-fe110.ihenderson.com (202.123.95.81)  30.599 ms  17.972 ms  18.178 ms
    30  202-123-95-82.ihenderson.com (202.123.95.82)  34.263 ms  17.716 ms  17.940 ms
    found jumping between routers. If my suppose is WRONG, please correct me.


    2)
    Tested on server on Internet, run by "traceroute.org"
    Code:
    Version: v1.0 Date: 22-Jan-2002
    Tracing route to 202-123-77-196.ihenderson.com [202.123.77.196]
    over a maximum of 30 hops:
      1   <10 ms   <10 ms   <10 ms  202.85.152.2 
      2   <10 ms   <10 ms   <10 ms  ge1-2-cosw0907.hk01.iadvantage.net [202.85.129.50] 
      3    57 ms   235 ms   223 ms  henderson-rge.hkix.net [202.40.161.105] 
      4     2 ms     2 ms     2 ms  202-123-94-91.ihenderson.com [202.123.94.91] 
      5     2 ms     2 ms     2 ms  202-123-94-51.ihenderson.com [202.123.94.51] 
      6     2 ms     2 ms     2 ms  202-123-95-82.ihenderson.com [202.123.95.82] 
      7     2 ms     2 ms     3 ms  hdc-coreb-fe110.ihenderson.com [202.123.95.81] 
      8     2 ms     2 ms     3 ms  202-123-95-82.ihenderson.com [202.123.95.82] 
      9     2 ms     3 ms     2 ms  hdc-coreb-fe110.ihenderson.com [202.123.95.81] 
     10     2 ms     2 ms     2 ms  202-123-95-82.ihenderson.com [202.123.95.82] 
     11     3 ms     3 ms     3 ms  hdc-coreb-fe110.ihenderson.com [202.123.95.81] 
     12     2 ms     2 ms     2 ms  202-123-95-82.ihenderson.com [202.123.95.82] 
     13     2 ms     3 ms     3 ms  hdc-coreb-fe110.ihenderson.com [202.123.95.81] 
     14     3 ms     3 ms     2 ms  202-123-95-82.ihenderson.com [202.123.95.82] 
     15     3 ms     3 ms     3 ms  hdc-coreb-fe110.ihenderson.com [202.123.95.81] 
     16     3 ms     2 ms     3 ms  202-123-95-82.ihenderson.com [202.123.95.82] 
     17     2 ms     3 ms     2 ms  hdc-coreb-fe110.ihenderson.com [202.123.95.81] 
     18     2 ms     2 ms     3 ms  202-123-95-82.ihenderson.com [202.123.95.82] 
     19     3 ms     3 ms     3 ms  hdc-coreb-fe110.ihenderson.com [202.123.95.81] 
     20     3 ms     2 ms     3 ms  202-123-95-82.ihenderson.com [202.123.95.82] 
     21     3 ms     3 ms     3 ms  hdc-coreb-fe110.ihenderson.com [202.123.95.81] 
     22     3 ms     3 ms     3 ms  202-123-95-82.ihenderson.com [202.123.95.82] 
     23     4 ms     3 ms     3 ms  hdc-coreb-fe110.ihenderson.com [202.123.95.81] 
     24     3 ms     3 ms     3 ms  202-123-95-82.ihenderson.com [202.123.95.82] 
     25     3 ms     3 ms     3 ms  hdc-coreb-fe110.ihenderson.com [202.123.95.81] 
     26     3 ms     3 ms     3 ms  202-123-95-82.ihenderson.com [202.123.95.82] 
     27     4 ms     5 ms     3 ms  hdc-coreb-fe110.ihenderson.com [202.123.95.81] 
     28     4 ms     3 ms     3 ms  202-123-95-82.ihenderson.com [202.123.95.82] 
     29     3 ms     3 ms     3 ms  hdc-coreb-fe110.ihenderson.com [202.123.95.81] 
     30     3 ms     3 ms     3 ms  202-123-95-82.ihenderson.com [202.123.95.82] 
    Trace complete.
    
    HTTP/1.1 502 Gateway Error
    Server: Microsoft-IIS/5.0
    Date: Thu, 09 Feb 2006 05:51:23 GMT
    Connection: close
    Content-Length: 186
    Content-Type: text/html
    It indicates gateway error


    3)
    Tesed on FC3
    # traceroute 202.123.77.213
    Code:
    traceroute to 202.123.77.213 (202.123.77.213), 30 hops max, 38 byte packets
     1  203.88.164.1 (203.88.164.1)  27.979 ms  16.987 ms  16.785 ms
     2  202-123-94-67.ihenderson.com (202.123.94.67)  27.374 ms  17.286 ms  17.442 ms
     3  202-123-95-82.ihenderson.com (202.123.95.82)  27.671 ms  17.258 ms  17.430 ms
     4  202-123-77-222.ihenderson.com (202.123.77.222)  28.253 ms  18.010 ms  17.931 ms
     5  ns02.ihenderson.com (202.123.77.213)  28.815 ms  18.266 ms  17.677 ms
    Exited automatically.


    4)
    Tested on server on Internet, run by "traceroute.org"
    Code:
    Version: v1.0 Date: 22-Jan-2002 Copyright: Sum.com.hk
    Tracing route to ns02.ihenderson.com [202.123.77.213]
    over a maximum of 30 hops:
      1   <10 ms     1 ms   <10 ms  202.85.152.2 
      2   <10 ms   <10 ms   <10 ms  ge1-2-cosw0907.hk01.iadvantage.net [202.85.129.50] 
      3     2 ms     2 ms     2 ms  henderson-rge.hkix.net [202.40.161.105] 
      4     2 ms     2 ms     2 ms  202-123-94-91.ihenderson.com [202.123.94.91] 
      5     3 ms     2 ms     2 ms  202-123-94-51.ihenderson.com [202.123.94.51] 
      6     3 ms     2 ms     2 ms  202-123-95-82.ihenderson.com [202.123.95.82] 
      7     2 ms     4 ms     3 ms  202-123-77-218.ihenderson.com [202.123.77.218] 
      8     3 ms     2 ms     2 ms  ns02.ihenderson.com [202.123.77.213] 
    
    Trace complete.
    No error indicated.


    Now each time after booting up the PC I have to revert the order of nameservers on /etc/resolv.conf. Since they are seldomly changed. Can I run them as static IP. If YES, please advise which file shall I edit to effect the change, not running them as dynamic IP. Tks.

    Furthermore please help me to understand what are the possible causes on ISP server with this mistake generated. TIA

    B.R.
    satimis

  2. #2
    Linux User
    Join Date
    Apr 2005
    Location
    Ohio
    Posts
    326
    I would actually use dig to test name servers.. Some ISPs block icmp packets to the DNS servers so Ping and traceroute may not be very good tools for testing.

    dig @203.123.77.196 google.com

    dig @202.123.77.213 google.com

    dig is a dns lookup (domain internet groper)
    the @IPADDRESS specifies a specific DNS server to use for the query
    google.com is just a domiain name to test with, you can use any you like.
    itg-debian:/proc# dig @192.168.0.24 google.com
    dig @192.168.0.24 google.com

    ; <<>> DiG 9.2.4 <<>> @192.168.0.24 google.com
    ;; global options: printcmd
    ;; Got answer:
    ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 1710
    ;; flags: qr aa; QUERY: 1, ANSWER: 3, AUTHORITY: 4, ADDITIONAL: 4

    ;; QUESTION SECTION:
    ;google.com. IN A

    ;; ANSWER SECTION:
    google.com. 300 IN A 64.233.187.99
    google.com. 300 IN A 64.233.167.99
    google.com. 300 IN A 72.14.207.99

    ;; AUTHORITY SECTION:
    google.com. 345600 IN NS ns1.google.com.
    google.com. 345600 IN NS ns2.google.com.
    google.com. 345600 IN NS ns3.google.com.
    google.com. 345600 IN NS ns4.google.com.

    ;; ADDITIONAL SECTION:
    ns1.google.com. 345600 IN A 216.239.32.10
    ns2.google.com. 345600 IN A 216.239.34.10
    ns3.google.com. 345600 IN A 216.239.36.10
    ns4.google.com. 345600 IN A 216.239.38.10

    ;; Query time: 41 msec
    ;; SERVER: 192.168.0.24#53(192.168.0.24)
    ;; WHEN: Wed Feb 15 14:02:24 2006
    ;; MSG SIZE rcvd: 212

    This will do actual name queries against the servers.. just because the do or don't respond to a ping or traceroute doesn't mean they won't respond to actual DNS queries.

    Personally I would find this more usefull when testing DNS. epsecially if the server responds saying refused or connection refused, etc...
    Error Messages

    If lookup was not successful, one of these common error messages may display:

    Timed out - The server didn't respond to a request after a certain amount of time and a certain number of retries.
    No response from server - No name server is running on the server machine.
    No records - The server doesn't have resource records of the current query type for the host, although the hostname is valid.
    Nonexistent domain - The hostname or domain name doesn't exist.
    Connection refused -- Network is unreachable - The connection to the name or finger server couldn't be made at the current time.
    Server failure - The name server found an internal inconsistency in its database and couldn't return a valid answer.
    Refused - The name server refused to service the request.
    Format error - The name server found that the request packet wasn't in the proper format.

    Try dig and see what you get.


    /etc/resolv.conf is the file that contains the DNS server addresses.
    far...out

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