DNS weirdness

[#1]

That's two more outages in the last half hour...
What is going on ?!

[#2]

@pd @jelv we had some issues with the recent traffic management changes yesterday afternoon that caused high CPU load on the Ellacoya switches. These were reloaded early evening so I'd be interested to know whether or not your problems continued after this?

Quote from: adriantribe

Is there are any other test I should do when the lookup ability is down that would provide PlusNet techies with any helpful data for diagnosing and thus fixing the problem?

Yes, see here. In particular the IPCONFIG and NSLOOKUP commands.

Quote

Incidentally, can anyone explain why when I try to do an ipconfig /flushdns on my daughter's Windows Vista laptop, I get the message "The requested operation requires elevation"?

Yes, it will be something to do with User Access Control or her permissions. You could either try disabling UAC or alternatively click start, type 'cmd' in the search field but *don't* press enter. Instead right-click  'cmd.exe/ in the program list above and try selecting the 'Run as administrator' option.
BTW, are you still having problems too?

[#3]

@ Bob – still haven't managed to get a proper trace to run:
traceroute to 212.159.6.10 (212.159.6.10), 64 hops max, 40 byte packets
1  192.168.0.1 (192.168.0.1)  1.686 ms  11.055 ms  11.055 ms
2  lo0.plusnet.thn-ag2.plus.net (195.166.128.93)  31.773 ms *  79.191 ms
3  vl604.thn-gw1.plus.net (84.92.4.169)  26.166 ms  29.630 ms  25.798 ms
4  ae0-102.ptn-gw01.plus.net (212.159.1.53)  97.781 ms  153.601 ms  197.548 ms
5  * * *
6  * * ae0-102.ptn-gw01.plus.net (212.159.1.53)  26.356 ms !X
7  * * *
8  * * *
9  * * *
10  * * *
traceroute to 212.159.6.9 (212.159.6.9), 64 hops max, 40 byte packets
1  * 192.168.0.1 (192.168.0.1)  8.074 ms  1.020 ms
2  lo0.plusnet.thn-ag2.plus.net (195.166.128.93)  26.884 ms  26.701 ms  137.832 ms
3  vl604.thn-gw1.plus.net (84.92.4.169)  35.721 ms  45.878 ms  81.056 ms
4  ae0-102.ptn-gw01.plus.net (212.159.1.53)  27.576 ms  27.196 ms  25.824 ms
5  * * *
6  * * *
7  * * *
8  * * *
9  * * *
10  * * *
maybe it's just something to do with me being on 21CN trial - and on a mac?  I dunno…

[#4]

Hi Bob
Worse than ever today  - very difficult even to access plus net member center.(!)
ipconfig
Host Name . . . . . . . . . . . . : Mick
  Primary Dns Suffix  . . . . . . . :
  Node Type . . . . . . . . . . . . : Hybrid
  IP Routing Enabled. . . . . . . . : No
  WINS Proxy Enabled. . . . . . . . : No
Ethernet adapter Local Area Connection:
  Connection-specific DNS Suffix  . :
  Description . . . . . . . . . . . : Realtek RTL8139/810x Family Fast Ethernet
NIC
  Physical Address. . . . . . . . . : 00-01-2E-10-61-93
  DHCP Enabled. . . . . . . . . . . : Yes
  Autoconfiguration Enabled . . . . : Yes
  Link-local IPv6 Address . . . . . : fe80::3d18:1d6e:6c4c:f752%8(Preferred)
  IPv4 Address. . . . . . . . . . . : 192.168.0.2(Preferred)
  Subnet Mask . . . . . . . . . . . : 255.255.255.0
  Lease Obtained. . . . . . . . . . : 17 July 2009 19:18:11
  Lease Expires . . . . . . . . . . : 20 July 2009 19:18:11
  Default Gateway . . . . . . . . . : 192.168.0.1
  DHCP Server . . . . . . . . . . . : 192.168.0.1
  DHCPv6 IAID . . . . . . . . . . . : 134218030
  DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-0F-48-B4-4D-00-01-2E-10-61-93
  DNS Servers . . . . . . . . . . . : 212.159.13.50
                                      212.159.13.49
  NetBIOS over Tcpip. . . . . . . . : Enabled

C:\>nslookup bbc.co.uk 212.159.13.50
DNS request timed out.
    timeout was 2 seconds.
Server:  UnKnown
Address:  212.159.13.50
DNS request timed out.
    timeout was 2 seconds.
DNS request timed out.
    timeout was 2 seconds.
DNS request timed out.
    timeout was 2 seconds.
DNS request timed out.
    timeout was 2 seconds.
*** Request to UnKnown timed-out
C:\>nslookup bbc.co.uk 212.159.13.49
DNS request timed out.
    timeout was 2 seconds.
Server:  UnKnown
Address:  212.159.13.49
DNS request timed out.
    timeout was 2 seconds.
DNS request timed out.
    timeout was 2 seconds.
DNS request timed out.
    timeout was 2 seconds.
DNS request timed out.
    timeout was 2 seconds.
*** Request to UnKnown timed-out

C:\>nslookup bbc.co.uk 212.159.13.49
Server:  pth-cdns01.plus.net
Address:  212.159.13.49
Non-authoritative answer:
Name:    bbc.co.uk
Address:  212.58.224.138

C:\>nslookup bbc.co.uk 212.159.13.50
Server:  pth-cdns02.plus.net
Address:  212.159.13.50
DNS request timed out.
    timeout was 2 seconds.
DNS request timed out.
    timeout was 2 seconds.
DNS request timed out.
    timeout was 2 seconds.
DNS request timed out.
    timeout was 2 seconds.
*** Request to pth-cdns02.plus.net timed-out
I repeated this and most times had the same result
Mick

[#5]

Hi
Tried this again later to check with this result

C:\>nslookup bbc.co.uk 212.159.13.50
Server: pth-cdns02.plus.net
Address: 212.159.13.50
Non-authoritative answer:
Name: bbc.co.uk
Address: 212.58.224.138

C:\>nslookup bbc.co.uk 212.159.13.49
Server: pth-cdns01.plus.net
Address: 212.159.13.49
Non-authoritative answer:
Name: bbc.co.uk
Address: 212.58.224.138

C:\>nslookup microsoft.com 212.159.13.49
Server: pth-cdns01.plus.net
Address: 212.159.13.49
Non-authoritative answer:
Name: microsoft.com
Addresses: 207.46.197.32
207.46.232.182

C:\>nslookup microsoft.com 212.159.13.50
Server: pth-cdns02.plus.net
Address: 212.159.13.50
Non-authoritative answer:
Name: microsoft.com
Addresses: 207.46.232.182
207.46.197.32
Lets see what tomorrow brings?

[#6]

@ Bob,
Thank you for your reply.
Just had another period of no lookup ability, during which time I did an ipconfig /all.  The relevant part
of the results showed:
Ethernet adapter Wireless Network Connection:
        Connection-specific DNS Suffix  . : home
        Description . . . . . . . . . . . : Intel(R) PRO/Wireless 3945ABG Network Connection
        Physical Address. . . . . . . . . : 00-1F-3C-97-78-99
        Dhcp Enabled. . . . . . . . . . . : Yes
        Autoconfiguration Enabled . . . . : Yes
        IP Address. . . . . . . . . . . . : 192.168.1.2
        Subnet Mask . . . . . . . . . . . : 255.255.255.0
        Default Gateway . . . . . . . . . : 192.168.1.1
        DHCP Server . . . . . . . . . . . : 192.168.1.1
        DNS Servers . . . . . . . . . . . : 192.168.1.1
        Lease Obtained. . . . . . . . . . : 17 July 2009 22:35:47
        Lease Expires . . . . . . . . . . : 18 July 2009 22:35:47
So I checked on the router instead, which showed that the DNS servers were set to:
Primary DNS Server 212.159.6.10
Secondary DNS Server 212.159.6.9
Before I was able to do an nslookup against one of these my full connectivity was
restored, so I don't know the outcome of that particular test.
I'll check again tomorrow, but in summary, the problems are still continuing.

[#7]

Windows should be set to get DNS server addresses automatically - doesn't look as though it is
Instructions here http://www.mediacollege.com/computer/network/dns.html

[#8]

Looks as expected to me Jim. The router is the DHCP server, the PC will get the DNS server to use from the DHCP server which will be itself. My Netgear DG834 does that and I believe most other routers will do the same.
Before I changed to Treewalk I explicitly set the DNS servers on the PC to the PN servers - I found that over time the router got clogged up and needed rebooting. After I stopped using the DNS on the router it didn't need the periodic reboots.

[#9]

Comparing with mine - I am on Vista with get DNS servers automatically and I get this result
Default Gateway . . . . . . . . . : 192.168.0.1
DHCP Server . . . . . . . . . . . : 192.168.0.1
DHCPv6 IAID . . . . . . . . . . . : 184556109
DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-0F-2A-81-41-00-1A-4D-59-68-29
DNS Servers . . . . . . . . . . . : 208.67.222.222
                                    208.67.220.220

[#10]

What router do you have?

[#11]

Netgear DG834G v4 and i get the same result from an XP computer

[#12]

I've just tried changing mine to automatic (XP to DG834 v1) to confirm what I get:

Ethernet adapter Local Area Connection:
        Connection-specific DNS Suffix  . :
        Description . . . . . . . . . . . : Intel(R) PRO/1000 MT Network Connection
        Physical Address. . . . . . . . . : 00-0F-1F-9B-02-53
        Dhcp Enabled. . . . . . . . . . . : Yes
        Autoconfiguration Enabled . . . . : Yes
        IP Address. . . . . . . . . . . . : 192.168.0.9
        Subnet Mask . . . . . . . . . . . : 255.255.255.0
        Default Gateway . . . . . . . . . : 192.168.0.1
        DHCP Server . . . . . . . . . . . : 192.168.0.1
        DNS Servers . . . . . . . . . . . : 192.168.0.1
        Lease Obtained. . . . . . . . . . : 18 July 2009 23:15:04
        Lease Expires . . . . . . . . . . : 19 July 2009 23:15:04

Are you using standard Netgear firmware?

[#13]

Yes  V5.01.09

[#14]

I have still been having problems with an unreliable connection.
What I don't understand is that during the last problem period I
did an nslookup on, for example, the bbc web site, specifying
the PN DNS server 212.159.6.9 and actually got a result - it was
abe to lookup the name and return the IP address.
However, my web browser was still not able to find the site.
So basically I've given up on this issue being properly resolved.
I have for now hard-coded the openDNS name servers into my
router and this afternoon everything is working absolutely fine.
If this is likely to cause me problems in the long term then perhaps
someone would let me know and explain.

[#15]

Hiya,
Rather than hardcoding the DNS settings into your router, have you tried hardcoding our DNS settings on the TCP/IP configuration of your network card on your computer?
I think I've seen 2 complaints about DNS this weekend.  If there were more I would have escalated out to our networks team, buit it's not sounding like a generic problem.