APIPA

xcanuc

I have a question about APIPA.

I am studying with the Microsoft Academic Course books and in 270 they say that if you have an APIPA address APIPA looks for a DHCP server every 5 minutes until it receives a DHCP address and then when it does it is fine. In 293 they say that if you have an APIPA address you must restart to get a DHCP address. I looked at Microsoft's web site and they say that you need to restart to get a DHCP assigned address also.

Does anyone have a difinitive answer on it?

Thanks in advance.

sprkymrk

I can't say I've read the oficial way it's supposed to work, but from what I've seen a reboot or ipconfig/renew will do it immediately, but waiting a few minutes (never timed it) will do it too.

Danman32

I think I read on a practice exam or something that the DHCP client retries to get an address from a DHCP server.

It makes sense since when a normal DHCP address is received, the client will try and renew the lease half way through the lease. All that the DHCP client would need to do is pretend that the APIPA address was issued by a server, and has a lease of 10 minutes, in which case the renewal would be attempted in 5 minutes.

jpeezy55

I've had an exam question on this, and the correct answer to a question something like, "When you have an APIPA, what must you do to get an IP from the DHCP?" The answer was: Do Nothing.

APIPA assigned addresses will automatically look for a DHCP every 5 minutes or so until it finds one. You can speed it up by using ipconfig /renew or by rebooting the client machine. But in all theory and more importantly, in the "World of Microsoft", do nothing.

Remember, whatever Microsoft said was the best answer is the best answer (on the exam). In the real-world it may not be, but go with what they want to get the exam question correct.

zeus_r

Hi,
APIPA stands for Automatic Private IP Addressing, and a windows xp computer gets a APIPA, if there is some problem while trying to get an address from the DHCP, generally u will get an ip address of the form 16.254.*.*, and yes it is true that the APIPA service will look for a valid ip address from the DHCP server after every 5 mins, and it stops automatically when it gets a valid ip address.

Generally to get a valid ip u will have to release the IP address of the computer by using the Command ipconfig /release and then try to obtain a fresh ip using ipconfig /renew.

When you try to renew the ip address, if the connection to the DHCP server if fine, u should get a valid ip address, else u will get an error message like "Unable to connect to a DHCP server" or something related to non connectivity.

To reslove this problem u will have to check for the root cause, if there is a problem with the connection then rectify it, if it seems to working fine then resetting the WINSOCK, should help.
In windows xp sp2 a simple command "netsh winsock reset", should work.
In case of sp1 and earlier, u will have to delete the winsock folders from the registry and then reinstall TCP/IP client on the machine.
Bye

xcanuc wrote:

I have a question about APIPA.

I am studying with the Microsoft Academic Course books and in 270 they say that if you have an APIPA address APIPA looks for a DHCP server every 5 minutes until it receives a DHCP address and then when it does it is fine. In 293 they say that if you have an APIPA address you must restart to get a DHCP address. I looked at Microsoft's web site and they say that you need to restart to get a DHCP assigned address also.

Does anyone have a difinitive answer on it?

Thanks in advance.

Danman32

You mean 169.254.*.*, don't you?

zeus_r

Yeah sorry about that mistake, it should have been 169.254.*.*

Danman32 wrote:

You mean 169.254.*.*, don't you?

PCHoldmann

I know I have hade some problems with computers getting APIPA addresses, causing a bunch of firewall block logs, and correcting itself almost immediately, so I would say it keeps checking for addresses. IPCONFIG /Renew would force it to check immediately.

zeus_r

Hi,
I am planing to prepare for MCP, which book should i follow.

PCHoldmann wrote:

I know I have hade some problems with computers getting APIPA addresses, causing a bunch of firewall block logs, and correcting itself almost immediately, so I would say it keeps checking for addresses. IPCONFIG /Renew would force it to check immediately.

eurotrash

zeus_r wrote:

Hi,
I am planing to prepare for MCP, which book should i follow.

Probably a book relevant to the exam.

zeus_r

Thanx for the information sir, could u please tell me which book should i follow for 70-270

_omni_ wrote:

zeus_r wrote:

Hi,
I am planing to prepare for MCP, which book should i follow.

Probably a book relevant to the exam.

eurotrash

zeus_r wrote:

Thanx for the information sir, could u please tell me which book should i follow for 70-270

_omni_ wrote:

zeus_r wrote:

Hi,
I am planing to prepare for MCP, which book should i follow.

Probably a book relevant to the exam.

Read the reviews here.

voxic

zeus_r wrote:

Hi,
APIPA stands for Automatic Private IP Addressing, and a windows xp computer gets a APIPA, if there is some problem while trying to get an address from the DHCP, generally u will get an ip address of the form 16.254.*.*, and yes it is true that the APIPA service will look for a valid ip address from the DHCP server after every 5 mins, and it stops automatically when it gets a valid ip address.

Generally to get a valid ip u will have to release the IP address of the computer by using the Command ipconfig /release and then try to obtain a fresh ip using ipconfig /renew.

When you try to renew the ip address, if the connection to the DHCP server if fine, u should get a valid ip address, else u will get an error message like "Unable to connect to a DHCP server" or something related to non connectivity.

To reslove this problem u will have to check for the root cause, if there is a problem with the connection then rectify it, if it seems to working fine then resetting the WINSOCK, should help.
In windows xp sp2 a simple command "netsh winsock reset", should work.
In case of sp1 and earlier, u will have to delete the winsock folders from the registry and then reinstall TCP/IP client on the machine.
Bye

xcanuc wrote:

I have a question about APIPA.

I am studying with the Microsoft Academic Course books and in 270 they say that if you have an APIPA address APIPA looks for a DHCP server every 5 minutes until it receives a DHCP address and then when it does it is fine. In 293 they say that if you have an APIPA address you must restart to get a DHCP address. I looked at Microsoft's web site and they say that you need to restart to get a DHCP assigned address also.

Does anyone have a difinitive answer on it?

Thanks in advance.

IPCONFIG /release will do nothing with APIPA. Instead it will say "this adapter has already been released" Just do a normal IPCONFIG/RENEW, you don't need the added first step.


APIPA in XP is a biatch...at least pre SP2 it was. When I worked for a large ISP the APIPA would often not successfully acquire an address on an ipconfig/renew even when everything was kosher with the DHCP source. Often I would find that rebooting was the only thing that worked. I'm pretty sure it was a glitch with it in XP. I do not know if it still like this in XP SP2. I haven't seen problems with it for a long time.

Also, you can't "uninstall" tcp/ip in XP. You have to reinstall tcp/ip onto itself when fixing a WINSOCK issue the old way. I'm not nitpicking, the only reason I brought this up is because I could imagine someone reading the post and then coming back complaining that the "uninstall" tcp/ip button was grayed out. It's supposed to be.

zeus_r

Yeah, by reinstall i meant reset, thanx for the clarification

voxic wrote:

zeus_r wrote:

Hi,
APIPA stands for Automatic Private IP Addressing, and a windows xp computer gets a APIPA, if there is some problem while trying to get an address from the DHCP, generally u will get an ip address of the form 16.254.*.*, and yes it is true that the APIPA service will look for a valid ip address from the DHCP server after every 5 mins, and it stops automatically when it gets a valid ip address.

Generally to get a valid ip u will have to release the IP address of the computer by using the Command ipconfig /release and then try to obtain a fresh ip using ipconfig /renew.

When you try to renew the ip address, if the connection to the DHCP server if fine, u should get a valid ip address, else u will get an error message like "Unable to connect to a DHCP server" or something related to non connectivity.

To reslove this problem u will have to check for the root cause, if there is a problem with the connection then rectify it, if it seems to working fine then resetting the WINSOCK, should help.
In windows xp sp2 a simple command "netsh winsock reset", should work.
In case of sp1 and earlier, u will have to delete the winsock folders from the registry and then reinstall TCP/IP client on the machine.
Bye

xcanuc wrote:

I have a question about APIPA.

I am studying with the Microsoft Academic Course books and in 270 they say that if you have an APIPA address APIPA looks for a DHCP server every 5 minutes until it receives a DHCP address and then when it does it is fine. In 293 they say that if you have an APIPA address you must restart to get a DHCP address. I looked at Microsoft's web site and they say that you need to restart to get a DHCP assigned address also.

Does anyone have a difinitive answer on it?

Thanks in advance.

IPCONFIG /release will do nothing with APIPA. Instead it will say "this adapter has already been released" Just do a normal IPCONFIG/RENEW, you don't need the added first step.


APIPA in XP is a biatch...at least pre SP2 it was. When I worked for a large ISP the APIPA would often not successfully acquire an address on an ipconfig/renew even when everything was kosher with the DHCP source. Often I would find that rebooting was the only thing that worked. I'm pretty sure it was a glitch with it in XP. I do not know if it still like this in XP SP2. I haven't seen problems with it for a long time.

Also, you can't "uninstall" tcp/ip in XP. You have to reinstall tcp/ip onto itself when fixing a WINSOCK issue the old way. I'm not nitpicking, the only reason I brought this up is because I could imagine someone reading the post and then coming back complaining that the "uninstall" tcp/ip button was grayed out. It's supposed to be.

xcanuc

Thanks for everyones help. I passed 270 today with a 826. WOO HOO!!!!!!

Megadeth4168

Congrats!

Danman32

Excellent work! Congrats!

!30

Congrat's to you Good luck on next one's !

xcanuc

Thanks for the grats everyone. Best of luck to !30 who is writing tomorrow.