Apparently-working PC PINGs at 10.xx.yy.zz address

[John Gray]

I hope this is the last of my network problems here!

One of four Windows 7 Pro PCs (PC04) on the LAN appears to be working well:
* it can ping itself by name as 192.168.1.77 (DHCP-assigned, by the router)
* it runs browsers happily
* other PCs on the LAN can map a drive letter to one of its shares
BUT
* when other PCs try to PING it (PING -4 -n 2 PC04), they get:
Pinging PC04.gateway.2wire.net [10.36.252.198] with 32 bytes of data:
Request timed out.
Request timed out.
Ping statistics for 10.36.252.198:
Packets: Sent = 2, Received = 0, Lost = 2 (100% loss),

I have no idea why a 10. address should be returned! What can I do? Thanks!

PS I have run IPCONFIG /FLUSHDNS and NBTSTAT -R on that PC yet again...

[Leif]

Does Ping a computer returns Ip address of a different give any clues?

(Googling "ping returns different ip address" returns quite a few hits, most of which are well beyond me...)

[John Gray]

Thanks, Lief. I tried IPCONFIG /REGISTERDNS but it didn't help.

In desperation I turned off the Norton Internet Security "smart" firewall, whose Trust Control had been set to Full Trust on all PCs, and the PING PC04 from a non-PC04 machine worked! So I changed the Trust Control to something, then back to Full Control, turned on the firewall, and PING PC04 from another machine now works. There's nowt so queer as computers....

[StuartR]

...
PS I have run IPCONFIG /FLUSHDNS and NBTSTAT -R on that PC yet again...

You would have needed to run these commands on all the other PCs, since the incorrect name translation was happening on the PC where you issued the ping command, not the one that was the target of the ping.

[John Gray]

I had run the two commands on all PCs on the previous day!
This specific problem seems to be a matter of "turn it off, turn it on again" for the NIS firewall.

[StuartR]

[John Gray]

I spoke too soon - the problem as originally specified has returned, and not even turning off the NIS firewall completely works....

[StuartR]

It looks like you probably have a bad name translation cached on a DNS server somewhere.

Please type the following commands on a PC that is trying (unsuccessfully) to ping the problem PC.

IPCONFIG /FLUSHDNS (this will make sure that any incorrect address isn't coming from the PC on which you are typing)
nslookup PC04.gateway.2wire.net (this will tell you what DNS server is giving you the invalid address)

You will probably see that the invalid address is coming from the DNS server in your home router, but let us know what output you get and we can proceed from there.

[John Gray]

Thanks, Stuart - here is PING and NSLOOKUP information for three PCs.

The offending GN04 has suddenly started being PINGable again, but NSLOOKUP fails.

The router is an olde BT 2700 HGV wireless router.

Code: Select all

PINGs --------------------------------------------------------------

Pinging PC02.gateway.2wire.net [192.168.1.74] with 32 bytes of data:
Reply from 192.168.1.74: bytes=32 time=2ms TTL=128
Reply from 192.168.1.74: bytes=32 time=2ms TTL=128
Ping statistics for 192.168.1.74:
    Packets: Sent = 2, Received = 2, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 2ms, Maximum = 2ms, Average = 2ms

Pinging PC03.gateway.2wire.net [192.168.1.76] with 32 bytes of data:
Reply from 192.168.1.76: bytes=32 time=101ms TTL=128
Reply from 192.168.1.76: bytes=32 time=2ms TTL=128
Ping statistics for 192.168.1.76:
    Packets: Sent = 2, Received = 2, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 2ms, Maximum = 101ms, Average = 51ms

Pinging PC04 [192.168.1.77] with 32 bytes of data:
Reply from 192.168.1.77: bytes=32 time=4ms TTL=128
Reply from 192.168.1.77: bytes=32 time=161ms TTL=128
Ping statistics for 192.168.1.77:
    Packets: Sent = 2, Received = 2, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
    Minimum = 4ms, Maximum = 161ms, Average = 82ms


NSLOOKUPs -----------------------------------------------------------

Server:  homeportal
Address:  192.168.1.254
Name:    PC02.gateway.2wire.net
Addresses:  192.168.1.74
	  192.168.1.74

Server:  homeportal
Address:  192.168.1.254
Name:    PC03.gateway.2wire.net
Addresses:  192.168.1.76
	  192.168.1.76

*** homeportal can't find PC04.gateway.2wire.net: Query refused
Server:  homeportal
Address:  192.168.1.254

[StuartR]

It looks like PC04 hasn't been registered correctly on the DNS server in your gateway. Let's try reassigning it's IP address from the gateway and see if that helps.

On PC04
ipconfig / registerdns

Then wait 15 minutes and retry the nslookup commands above.

[John Gray]

I've added in the offending DNS name and its IP address directly into the router (they weren't there previously, I discover) and I hope any change to the DHCP-assigned IP address will happen automatically.

I do notice an entry for "unknownB8AC6F9CA6E9" which is the MAC of the PC's NIC.

The router is so old/stupid that there doesn't seem to be a way of removing obsolete entries from the name resolution table.

[StuartR]

Issues like that can usually be resolved with the ipconfig / registerdns command that I suggested.

[John Gray]

Sadly not this time! I removed the router table entry manually and did ipconfig /registerdns on PC04, then went to lunch. Over an hour later, the entry wasn't inserted in the table - so I put it in again manually.

I am trying to get them to get BT to give them a new router...

[StuartR]

It might have been worth trying
ipconfig /release
wait a few minutes
ipconfig /renew

The trouble with the hard coded DNS entry is what happens if the DHCP server on the router decides to issue a different IP address some time. Will it let you hard code that DHCP IP address to the MAC address of the PC?

[John Gray]

I see your point, and I was considering taking it out of DHCP and manually giving it a fixed IP address.

I'm back there on Friday, and will try the release->renew then.