[ale] can anyone explain this? - the verdict

Christopher Bergeron christopher at bergeron.com
Tue Dec 18 21:27:17 EST 2001


Okay, well here's the [tenatively] final word:

The box stopped doing it.  I have no idea why;  I _know_ it was related to
DNS, and I changed a bunch of stuff on the DNS server at work today and I
made so many changes that I'm not sure exactly _which_ thing fixed the
problem.  But it no longer does it.  I can happily report that the only
"loss" I'm plagued with now is hair related.

I think it was a [somehow] circular DNS referennce and Windows somehow
"cheated" (cached or something) when it resolved...

Go figure.  I'm going to just chalk this one up to the annals of the unknown
(please note the spelling before flameing)  [ha! no pun intended either
(flameing - hehe)]

-CB



-----Original Message-----
From: tewkewl at mindspring.com [mailto:tewkewl at mindspring.com]
To: ale at ale.org
Sent: Tuesday, December 18, 2001 3:43 PM
To: cbergeron at bass-associates.com
Cc: 'Ale'
Subject: Re: RE: RE: Re: [ale] can anyone explain this?


try ping -i 5 www.bass-associates.com

that will wait 5 seconds between pings... are you familiar with tcpdump?
start a second console, an watch to see if you are sending dns requests.
Are you running nscd? (if the linux box is running named, it's not needed)

I've just never seen a box react that way.  Does it do it with all name
lookups?

-Patrick

cbergeron at bass-associates.com wrote:
> I get 0% packet loss.  However, when I do:
ping -c 10 -s 32 www.bass-associates.com

I get 66% loss.  I'm stumped.  Could it be my route?  It's 255.255.254.0
(see below on the 24.98 line) I'm not sure why...  any ideas?


I really do appreciate your help... but if we can't get it figured out,
it's no big deal really...



-----Original Message-----
From: tewkewl at mindspring.com [mailto:tewkewl at mindspring.com]
To: ale at ale.org
Sent: Tuesday, December 18, 2001 12:53 PM
To: Christopher Bergeron
Cc: Ale
Subject: Re: RE: Re: [ale] can anyone explain this?

try this

ping -c 10 -s 32 12.108.240.165

from the linux box.  that will send 10 pings @32bites and see if you
still get packet loss.

-Patrick

Christopher Bergeron  wrote:
> This is driving me nuts.  Here's some more data:
LINUX BOX (also the GATEWAY via eth1):

[root at proto1 /root]# ping www.bass-associates.com
PING www.bass-associates.com (12.108.240.165) from 24.98.82.217 : 56(84)
bytes of data.
--- www.bass-associates.com ping statistics ---
3 packets transmitted, 1 packets received, 66% packet loss
round-trip min/avg/max/mdev = 30.411/30.411/30.411/0.000 ms

[root at proto1 /root]# traceroute www.bass-associates.com
traceroute to www.bass-associates.com (12.108.240.165), 30 hops max, 38
byte
packets
 1  att-98-82-1.atl.mediaone.net (24.98.82.1)  7.345 ms  8.271 ms  7.678
ms
 2  rr-56-22-54.atl.mediaone.net (66.56.22.54)  28.624 ms  11.672 ms
21.400
ms
 3  rr-56-22-57.atl.mediaone.net (66.56.22.57)  9.031 ms  6.769 ms
8.252 ms
 4  rr-56-23-46.atl.mediaone.net (66.56.23.46)  9.011 ms  14.194 ms
9.000
ms
 5  stgsr01-POS2-0.atl.mediaone.net (66.56.66.30)  13.109 ms  28.920 ms
8.025 ms
 6  55-gsr2-POS3-0.atl.mediaone.net (66.56.66.10)  10.035 ms  10.396 ms
36.605 ms
 7  12.124.58.41 (12.124.58.41)  32.481 ms  15.510 ms  14.229 ms
 8  gbr6-p80.attga.ip.att.net (12.123.21.78)  9.914 ms  8.965 ms  10.398
ms
 9  gbr3-p80.attga.ip.att.net (12.122.5.46)  52.657 ms  10.544 ms
15.591 ms
10  gbr4-p40.ormfl.ip.att.net (12.122.2.182)  18.289 ms  21.284 ms
24.423
ms
11  gbr1-p90.ormfl.ip.att.net (12.122.5.126)  18.136 ms  19.502 ms
20.712
ms
12  ar4-a3120s2.ormfl.ip.att.net (12.123.32.61)  19.680 ms  27.440 ms
37.296 ms
13  206.121.224.234 (206.121.224.234)  53.893 ms  30.685 ms  34.200 ms
14  * * *
(15-24 * * * 's truncated for brevity )
25  * * *

[root at proto1 /root]# route
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use
Iface
192.168.0.0     *               255.255.255.0   U     0      0        0
eth0
24.98.82.0      *               255.255.254.0   U     0      0        0
eth1
127.0.0.0       *               255.0.0.0       U     0      0        0
lo
default         att-98-82-1.atl 0.0.0.0         UG    0      0        0
eth1




------------------------------------------------------------------------
----
THE WINDOWS BOX:
------------------------------------------------------------------------
----
C:\>ping www.bass-associates.com

Pinging www.bass-associates.com [12.108.240.165] with 32 bytes of data:

Reply from 12.108.240.165: bytes=32 time=40ms TTL=241
Reply from 12.108.240.165: bytes=32 time=30ms TTL=241
Reply from 12.108.240.165: bytes=32 time=30ms TTL=241
Reply from 12.108.240.165: bytes=32 time=30ms TTL=241

Ping statistics for 12.108.240.165:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 30ms, Maximum =  40ms, Average =  32ms

C:\>tracert www.bass-associates.com

Tracing route to www.bass-associates.com [12.108.240.165]
over a maximum of 30 hops:

  1   route print
========================================================================
===
Interface List
0x1 ........................... MS TCP Loopback interface
0x3 ...00 02 e3 21 58 2c ...... NETGEAR FA311 Fast Ethernet PCI Adapter
========================================================================
===
========================================================================
===
Active Routes:
Network Destination        Netmask          Gateway       Interface
Metric
          0.0.0.0          0.0.0.0      192.168.0.1     192.168.0.2
1
        127.0.0.0        255.0.0.0        127.0.0.1       127.0.0.1
1
      192.168.0.0    255.255.255.0      192.168.0.2     192.168.0.2
1
      192.168.0.2  255.255.255.255        127.0.0.1       127.0.0.1
1
    192.168.0.255  255.255.255.255      192.168.0.2     192.168.0.2
1
        224.0.0.0        224.0.0.0      192.168.0.2     192.168.0.2
1
  255.255.255.255  255.255.255.255      192.168.0.2     192.168.0.2
1
Default Gateway:       192.168.0.1
========================================================================
===
Persistent Routes:
  None



The traceroute's are identical with the exception of the first hop that
the
winbox makes to the linux box.
The target (destination) box is a linux box too.

I give up.  If you guys can ping it with no packet loss, I'm happy.  If
I
can't ping it from home because my config is screwed so be it.  I can
ping
the rest of the world just fine.  And if you need more torture here's
the
ping result by IP only (no hostname).  I appreciate the assistance, but
I'm
convinced that somehow it's the fault of DNS.


LINUX BOX:
[root at proto1 /root]# ping 12.108.240.174
PING 12.108.240.174 (12.108.240.174) from 24.98.82.217 : 56(84) bytes of
data.
64 bytes from 12.108.240.174: icmp_seq=0 ttl=51 time=24.888 msec
64 bytes from 12.108.240.174: icmp_seq=1 ttl=51 time=29.949 msec
64 bytes from 12.108.240.174: icmp_seq=2 ttl=51 time=29.963 msec

--- 12.108.240.174 ping statistics ---
3 packets transmitted, 3 packets received, 0% packet loss
round-trip min/avg/max/mdev = 24.888/28.266/29.963/2.396 ms


WINDOWS BOX:
C:\>ping 12.108.240.174

Pinging 12.108.240.174 with 32 bytes of data:
Reply from 12.108.240.174: bytes=32 time=30ms TTL=50
Reply from 12.108.240.174: bytes=32 time=30ms TTL=50
Reply from 12.108.240.174: bytes=32 time=30ms TTL=50
Ping statistics for 12.108.240.174:
    Packets: Sent = 3, Received = 3, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 30ms, Maximum =  30ms, Average =  30ms






-----Original Message-----
From: tewkewl at mindspring.com [mailto:tewkewl at mindspring.com]
To: ale at ale.org
Sent: Monday, December 17, 2001 3:48 PM
To: cbergeron at bassemail.com
Cc: 'Ale'
Subject: Re: Re: [ale] can anyone explain this?


I really don't think it's dns.... I mean. you are resolving fine, and
resolving the same ip address in both pings.  once you resolve, it stays
in
the machines own cache for the time being, so you don't have to resolve
on
each ping.  What happens when you run ping against the ip address
instead of
the name?  From my external router, I sent 100 pings to you with a
datagram
of 100 and a 2 second time out.  I got a
100% response.

-Patrick


cbergeron at bassemail.com wrote:
> Here's an example of what I was talking about:

[root at proto1 /root]# ping -c 3 www.bass-associates.com
PING www.bass-associates.com (12.108.240.165) from 24.98.82.217 : 56(84)
bytes of data.
--- www.bass-associates.com ping statistics ---
3 packets transmitted, 1 packets received, 66% packet loss
round-trip min/avg/max/mdev = 29.307/29.307/29.307/0.000 ms


[root at proto1 /root]# ping -q -c 3 www.bass-associates.com
PING www.bass-associates.com (12.108.240.165) from 24.98.82.217 : 56(84)
bytes of data.
--- www.bass-associates.com ping statistics ---
3 packets transmitted, 3 packets received, 0% packet loss
round-trip min/avg/max/mdev = 29.554/29.827/29.972/0.239 ms

Pretty odd if you ask me.  I think the problem is my secondary DNS, but
I'm not certain just yet.  When I get home tonight, I will try tracing
the route from the Winbox and the Linbox to see how they differ (if at
all; I don't think they do).


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