How come IPConfig /flushdns doesn't work??.... [Archive]

Penang

October 23rd 08, 08:08 AM

Hi, all !

I've tested IPConfig /flushdns command and found out that it doesn't
work. But before I go on, here are some background details...

My connection to the net is via ADSL, dynamic link. In theory, the use
of the following 3 commands:-

ipconfig /flushdns
ipconfig /release
ipconfig /renew

supposed to flush out the "old" dns, and obtain a "new" one.

So I made a batch file (ip.bat) with the following command:-

ipconfig /flushdns
ipconfig /release
ipconfig /renew
ipconfig /all

and run 2 tests, about 20 minutes apart.

The result is, the dns and the IPs stayed the same !!

The IP for test #1 is 118.101.50.219, so is test #2 !

I wonder if I have done something wrong. If I do, please tell me.

Thank you !

= = = = =============================================

Here are the complete test results: ----

Test #1:

D:\>ipconfig/flushdns

Windows IP Configuration
Successfully flushed the DNS Resolver Cache.

D:\>ipconfig/release

Windows IP Configuration

Ethernet adapter Local Area Connection:
Connection-specific DNS Suffix . :
IP Address. . . . . . . . . . . . : 0.0.0.0
Subnet Mask . . . . . . . . . . . : 0.0.0.0
Default Gateway . . . . . . . . . :

PPP adapter {9552DD77-E324-4E85-B801-1C1B61CACEF1}:
Connection-specific DNS Suffix . :
IP Address. . . . . . . . . . . . : 118.101.50.219
Subnet Mask . . . . . . . . . . . : 255.255.255.255
Default Gateway . . . . . . . . . : 118.101.50.219

D:\>ipconfig/renew

Windows IP Configuration

Ethernet adapter Local Area Connection:

Connection-specific DNS Suffix . :
IP Address. . . . . . . . . . . . : 192.168.1.3
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 192.168.1.1

PPP adapter {9552DD77-E324-4E85-B801-1C1B61CACEF1}:
Connection-specific DNS Suffix . :
IP Address. . . . . . . . . . . . : 118.101.50.219
Subnet Mask . . . . . . . . . . . : 255.255.255.255
Default Gateway . . . . . . . . . : 118.101.50.219

D:\>ipconfig/all

Windows IP Configuration

Host Name . . . . . . . . . . . . : MetalShaving
Primary Dns Suffix . . . . . . . :
Node Type . . . . . . . . . . . . : Unknown
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No

Ethernet adapter Local Area Connection:
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : VIA Compatable Fast
Ethernet Adapter #2
Physical Address. . . . . . . . . : 00-E0-4D-32-CE-8F
Dhcp Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
IP Address. . . . . . . . . . . . : 192.168.1.3
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. . . . . . . . . . : Wednesday, October 22,
2008 11:33:36 PM
Lease Expires . . . . . . . . . . : Friday, November 21,
2008 11:33:36 PM

PPP adapter {9552DD77-E324-4E85-B801-1C1B61CACEF1}:
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : WAN (PPP/SLIP) Interface
Physical Address. . . . . . . . . : 00-53-45-00-00-00
Dhcp Enabled. . . . . . . . . . . : No
IP Address. . . . . . . . . . . . : 118.101.50.219
Subnet Mask . . . . . . . . . . . : 255.255.255.255
Default Gateway . . . . . . . . . : 118.101.50.219
DNS Servers . . . . . . . . . . . : 202.188.0.133
202.188.1.5

Test #2:

D:\>ipconfig/flushdns

Windows IP Configuration
Successfully flushed the DNS Resolver Cache.

D:\>ipconfig/release

Windows IP Configuration

Ethernet adapter Local Area Connection:
Connection-specific DNS Suffix . :
IP Address. . . . . . . . . . . . : 0.0.0.0
Subnet Mask . . . . . . . . . . . : 0.0.0.0
Default Gateway . . . . . . . . . :

PPP adapter {9552DD77-E324-4E85-B801-1C1B61CACEF1}:
Connection-specific DNS Suffix . :
IP Address. . . . . . . . . . . . : 118.101.50.219
Subnet Mask . . . . . . . . . . . : 255.255.255.255
Default Gateway . . . . . . . . . : 118.101.50.219

D:\>ipconfig/renew

Windows IP Configuration

Ethernet adapter Local Area Connection:

Connection-specific DNS Suffix . :
IP Address. . . . . . . . . . . . : 192.168.1.3
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 192.168.1.1

PPP adapter {9552DD77-E324-4E85-B801-1C1B61CACEF1}:
Connection-specific DNS Suffix . :
IP Address. . . . . . . . . . . . : 118.101.50.219
Subnet Mask . . . . . . . . . . . : 255.255.255.255
Default Gateway . . . . . . . . . : 118.101.50.219

D:\>ipconfig/all

Windows IP Configuration

Host Name . . . . . . . . . . . . : MetalShaving
Primary Dns Suffix . . . . . . . :
Node Type . . . . . . . . . . . . : Unknown
IP Routing Enabled. . . . . . . . : No
WINS Proxy Enabled. . . . . . . . : No

Ethernet adapter Local Area Connection:
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : VIA Compatable Fast
Ethernet Adapter #2
Physical Address. . . . . . . . . : 00-E0-4D-32-CE-8F
Dhcp Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
IP Address. . . . . . . . . . . . : 192.168.1.3
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. . . . . . . . . . : Wednesday, October 22,
2008 11:58:36 PM
Lease Expires . . . . . . . . . . : Friday, November 21,
2008 11:58:36 PM

PPP adapter {9552DD77-E324-4E85-B801-1C1B61CACEF1}:
Connection-specific DNS Suffix . :
Description . . . . . . . . . . . : WAN (PPP/SLIP) Interface
Physical Address. . . . . . . . . : 00-53-45-00-00-00
Dhcp Enabled. . . . . . . . . . . : No
IP Address. . . . . . . . . . . . : 118.101.50.219
Subnet Mask . . . . . . . . . . . : 255.255.255.255
Default Gateway . . . . . . . . . : 118.101.50.219
DNS Servers . . . . . . . . . . . : 202.188.0.133
202.188.1.5

MEB[_2_]

October 23rd 08, 08:53 AM

"Penang" > wrote in message
...
| Hi, all !
|
| I've tested IPConfig /flushdns command and found out that it doesn't
| work. But before I go on, here are some background details...
|
|My connection to the net is via ADSL, dynamic link. In theory, the use
|of the following 3 commands:-
|***IP config info cut****

So what's your problem? And why all these cross-posts....

*You* obtain your IP and other from the modem/router when dynamic.
Want a new address? Physically power down [disconnect from power for about
20 minutes] the modem/router though its likely assigned via your provider
and hard set when initially installed [they have to know who you are after
all].
*IF* you received software with the ADSL modem you may be able to adjust the
*local IP ranges* .... you must contact your provider if you want to change
the ADSL IP/device ID.

--
MEB
http://peoplescounsel.org
a Peoples' counsel
_ _
~~

ZÿRiX

October 23rd 08, 10:29 AM

1. release before flush
2. you are still connected the same device so you will pick up
the same ip as it has a lease time to it...
Devices that have not been changed almost always keep the same ip
Example...you have cable internet and you shut down your computer
and restart it most likely you will have the same ip but change the
network card and the mac address changes so the modem will
see a NEW device and the ip will change...
Same works for changing routers.....

Create a batch with this just copy and paste

@echo off

ipconfig /release
pause
ipconfig /flushdns
pause
ipconfig /renew
pause
ipconfig /all

--
ZÿRiX
(¯`'..(<>..<>)..'´¯)

Sinner

October 23rd 08, 01:12 PM

"MEB" <meb@not > wrote in message ...
>
> *You* obtain your IP and other from the modem/router when dynamic.
> Want a new address? Physically power down [disconnect from power for about
> 20 minutes] the modem/router though its likely assigned via your provider
> and hard set when initially installed [they have to know who you are after
> all].
> *IF* you received software with the ADSL modem you may be able to adjust the
> *local IP ranges* .... you must contact your provider if you want to change
> the ADSL IP/device ID.
>

My former service provider, a cable service, told me my IP was dynamic also. In fact, they have a finite number of IP addresses, and for me to get a new one, I'd have to power down for at least 3 days. Anything less, and I'd just be reassigned the same address when I logged back on.

My current provider, Bellsouth FastAccess, has provides me with a Static IP. It's great if you want to self-host a website, FTP server, etc., but it sucks if your IP has been banned by several forums. For that, they invented the Proxy Server.

ZÿRiX

October 23rd 08, 01:45 PM

My former service provider, a cable service, told me my IP was dynamic also.
In fact, they have a finite number of IP addresses, and for me to get a new
one, I'd have to power down for at least 3 days. Anything less, and I'd
just be reassigned the same address when I logged back on.

With cable change your router or change the mac in the router and it will
change your IP most times...

--
ZÿRiX
(¯`'..(<>..<>)..'´¯)

Jack \(MVP-Networking\).

October 23rd 08, 04:11 PM

Hi
Dynamic IP from the ISP does not imply that every time you log On or Off the
IP would change.
It means that you are Not entrusted with one specific IP, but the schedule
of the dynamic changes are up to the ISP's server.
Some ISP's IPs do not change for weeks even if you disconnect the modem from
the line, and reconnect after few days.
BTW, flushdns is a local command and does not affect the Internet connection
per-se.
Jack (MS, MVP-Networking)

"Penang" > wrote in message
...
> Hi, all !
>
> I've tested IPConfig /flushdns command and found out that it doesn't
> work. But before I go on, here are some background details...
>
> My connection to the net is via ADSL, dynamic link. In theory, the use
> of the following 3 commands:-
>
> ipconfig /flushdns
> ipconfig /release
> ipconfig /renew
>
> supposed to flush out the "old" dns, and obtain a "new" one.
>
> So I made a batch file (ip.bat) with the following command:-
>
> ipconfig /flushdns
> ipconfig /release
> ipconfig /renew
> ipconfig /all
>
> and run 2 tests, about 20 minutes apart.
>
> The result is, the dns and the IPs stayed the same !!
>
> The IP for test #1 is 118.101.50.219, so is test #2 !
>
> I wonder if I have done something wrong. If I do, please tell me.
>
> Thank you !
>
>
> = = = = =============================================
>
>
> Here are the complete test results: ----
>
> Test #1:
>
> D:\>ipconfig/flushdns
>
> Windows IP Configuration
> Successfully flushed the DNS Resolver Cache.
>
> D:\>ipconfig/release
>
> Windows IP Configuration
>
>
> Ethernet adapter Local Area Connection:
> Connection-specific DNS Suffix . :
> IP Address. . . . . . . . . . . . : 0.0.0.0
> Subnet Mask . . . . . . . . . . . : 0.0.0.0
> Default Gateway . . . . . . . . . :
>
> PPP adapter {9552DD77-E324-4E85-B801-1C1B61CACEF1}:
> Connection-specific DNS Suffix . :
> IP Address. . . . . . . . . . . . : 118.101.50.219
> Subnet Mask . . . . . . . . . . . : 255.255.255.255
> Default Gateway . . . . . . . . . : 118.101.50.219
>
>
> D:\>ipconfig/renew
>
> Windows IP Configuration
>
> Ethernet adapter Local Area Connection:
>
> Connection-specific DNS Suffix . :
> IP Address. . . . . . . . . . . . : 192.168.1.3
> Subnet Mask . . . . . . . . . . . : 255.255.255.0
> Default Gateway . . . . . . . . . : 192.168.1.1
>
> PPP adapter {9552DD77-E324-4E85-B801-1C1B61CACEF1}:
> Connection-specific DNS Suffix . :
> IP Address. . . . . . . . . . . . : 118.101.50.219
> Subnet Mask . . . . . . . . . . . : 255.255.255.255
> Default Gateway . . . . . . . . . : 118.101.50.219
>
> D:\>ipconfig/all
>
> Windows IP Configuration
>
> Host Name . . . . . . . . . . . . : MetalShaving
> Primary Dns Suffix . . . . . . . :
> Node Type . . . . . . . . . . . . : Unknown
> IP Routing Enabled. . . . . . . . : No
> WINS Proxy Enabled. . . . . . . . : No
>
> Ethernet adapter Local Area Connection:
> Connection-specific DNS Suffix . :
> Description . . . . . . . . . . . : VIA Compatable Fast
> Ethernet Adapter #2
> Physical Address. . . . . . . . . : 00-E0-4D-32-CE-8F
> Dhcp Enabled. . . . . . . . . . . : Yes
> Autoconfiguration Enabled . . . . : Yes
> IP Address. . . . . . . . . . . . : 192.168.1.3
> 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. . . . . . . . . . : Wednesday, October 22,
> 2008 11:33:36 PM
> Lease Expires . . . . . . . . . . : Friday, November 21,
> 2008 11:33:36 PM
>
> PPP adapter {9552DD77-E324-4E85-B801-1C1B61CACEF1}:
> Connection-specific DNS Suffix . :
> Description . . . . . . . . . . . : WAN (PPP/SLIP) Interface
> Physical Address. . . . . . . . . : 00-53-45-00-00-00
> Dhcp Enabled. . . . . . . . . . . : No
> IP Address. . . . . . . . . . . . : 118.101.50.219
> Subnet Mask . . . . . . . . . . . : 255.255.255.255
> Default Gateway . . . . . . . . . : 118.101.50.219
> DNS Servers . . . . . . . . . . . : 202.188.0.133
> 202.188.1.5
>
>
> Test #2:
>
>
> D:\>ipconfig/flushdns
>
> Windows IP Configuration
> Successfully flushed the DNS Resolver Cache.
>
> D:\>ipconfig/release
>
> Windows IP Configuration
>
>
> Ethernet adapter Local Area Connection:
> Connection-specific DNS Suffix . :
> IP Address. . . . . . . . . . . . : 0.0.0.0
> Subnet Mask . . . . . . . . . . . : 0.0.0.0
> Default Gateway . . . . . . . . . :
>
> PPP adapter {9552DD77-E324-4E85-B801-1C1B61CACEF1}:
> Connection-specific DNS Suffix . :
> IP Address. . . . . . . . . . . . : 118.101.50.219
> Subnet Mask . . . . . . . . . . . : 255.255.255.255
> Default Gateway . . . . . . . . . : 118.101.50.219
>
>
> D:\>ipconfig/renew
>
> Windows IP Configuration
>
> Ethernet adapter Local Area Connection:
>
> Connection-specific DNS Suffix . :
> IP Address. . . . . . . . . . . . : 192.168.1.3
> Subnet Mask . . . . . . . . . . . : 255.255.255.0
> Default Gateway . . . . . . . . . : 192.168.1.1
>
> PPP adapter {9552DD77-E324-4E85-B801-1C1B61CACEF1}:
> Connection-specific DNS Suffix . :
> IP Address. . . . . . . . . . . . : 118.101.50.219
> Subnet Mask . . . . . . . . . . . : 255.255.255.255
> Default Gateway . . . . . . . . . : 118.101.50.219
>
> D:\>ipconfig/all
>
> Windows IP Configuration
>
> Host Name . . . . . . . . . . . . : MetalShaving
> Primary Dns Suffix . . . . . . . :
> Node Type . . . . . . . . . . . . : Unknown
> IP Routing Enabled. . . . . . . . : No
> WINS Proxy Enabled. . . . . . . . : No
>
> Ethernet adapter Local Area Connection:
> Connection-specific DNS Suffix . :
> Description . . . . . . . . . . . : VIA Compatable Fast
> Ethernet Adapter #2
> Physical Address. . . . . . . . . : 00-E0-4D-32-CE-8F
> Dhcp Enabled. . . . . . . . . . . : Yes
> Autoconfiguration Enabled . . . . : Yes
> IP Address. . . . . . . . . . . . : 192.168.1.3
> 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. . . . . . . . . . : Wednesday, October 22,
> 2008 11:58:36 PM
> Lease Expires . . . . . . . . . . : Friday, November 21,
> 2008 11:58:36 PM
>
> PPP adapter {9552DD77-E324-4E85-B801-1C1B61CACEF1}:
> Connection-specific DNS Suffix . :
> Description . . . . . . . . . . . : WAN (PPP/SLIP) Interface
> Physical Address. . . . . . . . . : 00-53-45-00-00-00
> Dhcp Enabled. . . . . . . . . . . : No
> IP Address. . . . . . . . . . . . : 118.101.50.219
> Subnet Mask . . . . . . . . . . . : 255.255.255.255
> Default Gateway . . . . . . . . . : 118.101.50.219
> DNS Servers . . . . . . . . . . . : 202.188.0.133
> 202.188.1.5

John Wunderlich

October 23rd 08, 08:22 PM

Penang > wrote in news:bbdc21c9-126b-4da5-b4fd-
:

> I've tested IPConfig /flushdns command and found out that it doesn't
> work. But before I go on, here are some background details...
>
>

You have a misunderstanding on how "flushdns" works. When connecting
to a site, a DNS lookup is made to find the IP address of that site.
After obtaining this information, that result is cached in a local
memory so that if you need to look up the same address in the near
future, you have it locally and don't have to go out to the DNS server
to look it up again.

Flushdns simply clears out this local DNS cache and forces the next
lookup to go to the DNS server to get its answer. You can't tell if it
worked by doing an "ipconfig" command.

-- John

Bruce Chambers

October 24th 08, 02:11 AM

Penang wrote:
> Hi, all !
>
> I've tested IPConfig /flushdns command and found out that it doesn't
> work. But before I go on, here are some background details...
>
> My connection to the net is via ADSL, dynamic link. In theory, the use
> of the following 3 commands:-
>
> ipconfig /flushdns
> ipconfig /release
> ipconfig /renew
>
> supposed to flush out the "old" dns, and obtain a "new" one.
>
> So I made a batch file (ip.bat) with the following command:-
>
> ipconfig /flushdns
> ipconfig /release
> ipconfig /renew
> ipconfig /all
>
> and run 2 tests, about 20 minutes apart.
>
> The result is, the dns and the IPs stayed the same !!
>
> The IP for test #1 is 118.101.50.219, so is test #2 !
>
> I wonder if I have done something wrong. If I do, please tell me.
>

If you want to ensure a new IP Address (with which the "\flushdns"
switch has *nothing* to do) you'll need to reboot the computer after
using the "/release" command. (It's also normal practice to reboot
after using the "\flushdns" command, as well.)

--

Bruce Chambers

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