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Windows 7: One network card but two IP'S ?

06 Sep 2013   #1
Nelly

Windows 7 Home Premium
 
 
One network card but two IP'S ?

Good morning,
I have one network card and are assigned two IP's by my router.
I have DHCP enabled and the adapter is set to obtain IP's automatically which then assigns two IP's.
This does not happen with any other PC's on the network.
Any suggestions / help ?
Thanks,Nelly


My System SpecsSystem Spec
.
06 Sep 2013   #2
Shadowjk

Windows 7 Professional x64 SP1 ; Windows Server 2012 R2 Standard
 
 

Following this will help us better understand what you mean - Basic Requirements Before Posting your Networking Thread

Are both addresses IPv4? - (XXX.XXX.XXX.XXX) Or is their one which is IPv6? - (XXXX:XXXX:XXXX:XXXX::X)

You can only have one IP address assigned per interface so following the above requirements will help us to see what the second IP address correlates to.

Josh
My System SpecsSystem Spec
06 Sep 2013   #3
Nelly

Windows 7 Home Premium
 
 

Thanks for the quick reply and link to the guide.

1. Is this a wired or wireless connection issue? Wired

2. Who is your Internet Service Provider (ISP)? BT

3. What type of Broadband connection are you using? DSL


4. What is the exact Make and Model of your Modem, Router or Modem/Router Combo ? BT Home Hub v2

5. What is the Name of the Anti-Virus, Security or Firewall Software installed from the problematic computer ?
AVG anti-virus and Comodo Firewall

Result of ipconfig /all :
Microsoft Windows [Version 6.1.7601]
Copyright (c) 2009 Microsoft Corporation. All rights reserved.

C:\Windows\System32>ipconfig /all

Windows IP Configuration

Host Name . . . . . . . . . . . . : Nellys-PC
Primary Dns Suffix . . . . . . . :
Node Type . . . . . . . . . . . . : Hybrid
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No
DNS Suffix Search List. . . . . . : home

Ethernet adapter Local Area Connection:

Connection-specific DNS Suffix . : home
Description . . . . . . . . . . . : Realtek PCI GBE Family Controller
Physical Address. . . . . . . . . : C8-3A-35-D7-70-91
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
IPv4 Address. . . . . . . . . . . : 192.168.1.135(Preferred)
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Lease Obtained. . . . . . . . . . : 06 September 2013 13:19:34
Lease Expires . . . . . . . . . . : 07 September 2013 13:19:34
Default Gateway . . . . . . . . . : 192.168.1.254
DHCP Server . . . . . . . . . . . : 192.168.1.254
DNS Servers . . . . . . . . . . . : 192.168.1.254
NetBIOS over Tcpip. . . . . . . . : Enabled

Tunnel adapter Teredo Tunneling Pseudo-Interface:

Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : Teredo Tunneling Pseudo-Interface
Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes
IPv6 Address. . . . . . . . . . . : 2001:0:5ef5:79fb:3c80:27ec:3f57:fe78(Preferred)
Link-local IPv6 Address . . . . . : fe80::3c80:27ec:3f57:fe78%12(Preferred)
Default Gateway . . . . . . . . . : ::
NetBIOS over Tcpip. . . . . . . . : Disabled

Tunnel adapter isatap.home:

Media State . . . . . . . . . . . : Media disconnected
Connection-specific DNS Suffix . : home
Description . . . . . . . . . . . : Microsoft ISATAP Adapter
Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
DHCP Enabled. . . . . . . . . . . : No
Autoconfiguration Enabled . . . . : Yes

C:\Windows\System32>

Both addresses are IPv4 (XXX.XXX.XXX.XXX)

Thanks again, Nelly.
My System SpecsSystem Spec
.

06 Sep 2013   #4
Shadowjk

Windows 7 Professional x64 SP1 ; Windows Server 2012 R2 Standard
 
 

Your ethernet adapter has one IP address assigned to it. The second IPv4 Address is your router's IP address of your router so that you machine knows how to get off the network to the internet.

This is normal configuration

I did notice that you have an IPv6 address assigned to your tunnel adapter however this shouldn't cause any issues. If you wish I can offer a possible solution to remove the IPv6 address? The choice is yours.

Hope This Helps,
Josh
My System SpecsSystem Spec
06 Sep 2013   #5
Nelly

Windows 7 Home Premium
 
 

Hello Josh,
Thanks for the assurance of normal operation. I believe I understand your reply : one IP is my PC and one is the "Gateway" to the Internet.
However, when two IP's are on the DHCP table and Network Map of the Hub. The MAC address of both IP's are the same showing that it's the same PC.
The "second" IP address does not end in 254.
Thanks again,Nelly.
p.s. Is it safe to show IP address's ? A bit late now I suppose. Would you delete my IP info please ?
My System SpecsSystem Spec
06 Sep 2013   #6
Shadowjk

Windows 7 Professional x64 SP1 ; Windows Server 2012 R2 Standard
 
 

Quote:
Thanks for the assurance of normal operation. I believe I understand your reply : one IP is my PC and one is the "Gateway" to the Internet.
You are correct.

Quote:
However, when two IP's are on the DHCP table and Network Map of the Hub. The MAC address of both IP's are the same showing that it's the same PC.
The "second" IP address does not end in 254.
Could be an old DHCP lease or it may be your tunnel adapter I do not know, will have to have see the DHCP table in order to better understand it.

Quote:
p.s. Is it safe to show IP address's ? A bit late now I suppose. Would you delete my IP info please ?
Completely safe, You are using private IP addresses which are used by millions all over the world so no-one can locate you via IP address.

Josh
My System SpecsSystem Spec
06 Sep 2013   #7
chamjiee

Windows 7 Ultimate x64 SP1 Dual Boot with Windows Serve 2012 R2
 
 

All appears normal from the perspective of your pc.

However if your router is showing two ips assigned to one mac then one of them might be an old lease. However I have never faced this situation where one mac was associated with two ip addresses .


Your router should reassign the same ip to your pc.

It's strange that your DHCP is holding a lease and not assigning it and rather creating a new lease.

Are you sure no one is spoofing the mac addresses in your network?


Try restarting your router to see if the issue is still there and also keep an eye on the tables for sometime.
My System SpecsSystem Spec
06 Sep 2013   #8
Shadowjk

Windows 7 Professional x64 SP1 ; Windows Server 2012 R2 Standard
 
 

If you do an ipconfig /renew the DHCP table will show a two leases for one MAC until one is expired.

Josh
My System SpecsSystem Spec
06 Sep 2013   #9
Nelly

Windows 7 Home Premium
 
 

Thanks again for the reassurances.
I've checked the DHCP table and there is , at the moment, only 1 IP address for my PC. I'll check tomorrow when the lease will have expired and see what the situation is then.
Thanks again, Nelly
My System SpecsSystem Spec
07 Sep 2013   #10
Nelly

Windows 7 Home Premium
 
 

Hello All,
Just checked the DHCP table and it's back (please see screenshot below)

One network card but two IP'S ?-dhcp-table.png

As you can see this does not occur with any other device on the network.
Thanks for any help,Nelly


My System SpecsSystem Spec
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 One network card but two IP'S ?




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