often need to stop and start DNS service....

  • Thread starter Thread starter Jim
  • Start date Start date
J

Jim

Not sure if the cable modem is having temporary loss of
signal (I've noticed that when the loss is long enough to
see on the modem indicators, restarting DNS reestablishes
communication), but whatever it is, is there a 'delay'
setting or something to prevent this need to stop and
start DNS to regain Internet communication from happening?

As a side note, and not sure if it's related, upon boot,
it usually hangs the first attempt -- just after and the
colorful Windows screen with the scroll bar at the bottom
and just before the network login blue background screen
comes up. It's a Windows 2000 OS. Thanks in advance.
 
Jim said:
Not sure if the cable modem is having temporary loss of
signal (I've noticed that when the loss is long enough to
see on the modem indicators, restarting DNS reestablishes
communication), but whatever it is, is there a 'delay'
setting or something to prevent this need to stop and
start DNS to regain Internet communication from happening?
Click to expand...

First, almost all DNS traffic is UDP/connectionless and even the
TCP traffic of DNS is very temporary, taking a few seconds usually
and then disconnecting.

So while it is possible that starting and stopping it is somehow
re-initializing the service it is very unlikely that it is actually the
communications (IP) part that is at fault.

The above problem doesn't occur for the vast majority so first
steps would be to check service packs, etc.

Also, NICs, drivers, and ESPECIALLY "Network drop cables"
which are notoriously bad AND notoriously overlooked on such
"weird" problems.
comes up. It's a Windows 2000 OS. Thanks in advance.
Click to expand...

Adding your Service Pack status to such reports would save time.
 
-----Original Message-----
happening?

First, almost all DNS traffic is UDP/connectionless and even the
TCP traffic of DNS is very temporary, taking a few seconds usually
and then disconnecting.

So while it is possible that starting and stopping it is somehow
re-initializing the service it is very unlikely that it is actually the
communications (IP) part that is at fault.

The above problem doesn't occur for the vast majority so first
steps would be to check service packs, etc.

Also, NICs, drivers, and ESPECIALLY "Network drop cables"
which are notoriously bad AND notoriously overlooked on such
"weird" problems.


Adding your Service Pack status to such reports would save time.
Click to expand...
Thanks so far. It is service pack 4. This problem began
a couple months ago and there haven't been any changes to
any hardware, network related or not, in over a year. I've
noticed that when I turn the cable modem off and back on,
it is necessary to either start and stop DNS service or
reboot in order to regain network communication.... From
what you've said already, should I (in order) first
replace the network cables, update the NIC driver, then
replace the NIC?
 
Thanks so far. It is service pack 4. This problem began
a couple months ago and there haven't been any changes to
any hardware, network related or not, in over a year. I've
noticed that when I turn the cable modem off and back on,
it is necessary to either start and stop DNS service or
reboot in order to regain network communication.... From
what you've said already, should I (in order) first
replace the network cables, update the NIC driver, then
replace the NIC?
Click to expand...

If you have any of these at hand, then I would look at trying
to substitute to solve the problem.

BUT, before you do that or start buying stuff -- what happens
if you just PING by IP address?

Does that work even though the DNS has to be restarted before
it works again?

What happens if you NSLookup to a SPECIFIC, external DNS
server (instead of using the internal one)?

nslookup www.LearnQuick.com IP.DNS.AT.ISP

If that works but the default (internal) doesn't, then maybe there
is some issue with your DNS server but this will help to isolate the
problem first.
 
Thanks so far. It is service pack 4. This problem began
a couple months ago and there haven't been any changes to
any hardware, network related or not, in over a year. I've
noticed that when I turn the cable modem off and back on,
it is necessary to either start and stop DNS service or
reboot in order to regain network communication.... From
what you've said already, should I (in order) first
replace the network cables, update the NIC driver, then
replace the NIC?
Click to expand...

After you reboot your cable modem--presuming you're directly connected to
it--you may need to run

ipconfig /renew

from a command prompt. Does that work?

If you're using a broadband router, you more likely need to reboot the
router after restarting the cable modem, so it can receive a new IP from the
cable modem.
 
Do you know about the root . ?

--
Jim Carlock
http://www.microcosmotalk.com/
Post replies to the newsgroup.


:
| Not sure if the cable modem is having temporary loss of
| signal (I've noticed that when the loss is long enough to
| see on the modem indicators, restarting DNS reestablishes
| communication), but whatever it is, is there a 'delay'
| setting or something to prevent this need to stop and
| start DNS to regain Internet communication from happening?
|
| As a side note, and not sure if it's related, upon boot,
| it usually hangs the first attempt -- just after and the
| colorful Windows screen with the scroll bar at the bottom
| and just before the network login blue background screen
| comes up. It's a Windows 2000 OS. Thanks in advance.
 
In
Thanks so far. It is service pack 4. This problem began
a couple months ago and there haven't been any changes to
any hardware, network related or not, in over a year. I've
noticed that when I turn the cable modem off and back on,
it is necessary to either start and stop DNS service or
reboot in order to regain network communication.... From
what you've said already, should I (in order) first
replace the network cables, update the NIC driver, then
replace the NIC?
Click to expand...


I remember seeing an article stating that if a DNS server is directly
connected to a cable modem or DSL modem that when the connection drops, then
the interface thinks it's down and causes the DNS service to hang and will
need to restart the DNS service, even if the connection comes back up. Now
if it's on a switch or hub, then the interface will always think that it's
"up" and the service won't drop out. I searched for the article, but cannot
find it... if I do, I'll post it.



--
Regards,
Ace

Please direct all replies to the newsgroup so all can benefit.
This posting is provided "AS-IS" with no warranties and confers no
rights.

Ace Fekay, MCSE 2000, MCSE+I, MCSA, MCT, MVP
Microsoft Windows MVP - Active Directory
 
Might be a bad connection as well. If the connection is dirty,
the DNS server might appear to be dropped when actually,
the line has some noise or cross signaling.

One way to test this is to do a bunch of tracert 's to see if
there's a common point at which the timing goes up or the
packets are lost. If the time listed is high one or two hops
away, then you might want to disconnect and reconnect
the cables to see if the timing gets below 10ms. I'm thinking
the timing for the first 3 or 4 hops should all be below 10ms.

--
Jim Carlock
http://www.microcosmotalk.com/
Post replies to the newsgroup.


"Ace Fekay [MVP]"
message In
Thanks so far. It is service pack 4. This problem began
a couple months ago and there haven't been any changes to
any hardware, network related or not, in over a year. I've
noticed that when I turn the cable modem off and back on,
it is necessary to either start and stop DNS service or
reboot in order to regain network communication.... From
what you've said already, should I (in order) first
replace the network cables, update the NIC driver, then
replace the NIC?
Click to expand...


I remember seeing an article stating that if a DNS server is directly
connected to a cable modem or DSL modem that when the connection drops, then
the interface thinks it's down and causes the DNS service to hang and will
need to restart the DNS service, even if the connection comes back up. Now
if it's on a switch or hub, then the interface will always think that it's
"up" and the service won't drop out. I searched for the article, but cannot
find it... if I do, I'll post it.



--
Regards,
Ace

Please direct all replies to the newsgroup so all can benefit.
This posting is provided "AS-IS" with no warranties and confers no
rights.

Ace Fekay, MCSE 2000, MCSE+I, MCSA, MCT, MVP
Microsoft Windows MVP - Active Directory
 
In
Jim Carlock said:
Might be a bad connection as well. If the connection is dirty,
the DNS server might appear to be dropped when actually,
the line has some noise or cross signaling.

One way to test this is to do a bunch of tracert 's to see if
there's a common point at which the timing goes up or the
packets are lost. If the time listed is high one or two hops
away, then you might want to disconnect and reconnect
the cables to see if the timing gets below 10ms. I'm thinking
the timing for the first 3 or 4 hops should all be below 10ms.
Click to expand...

Not a bad thought about a bad connection, such as a bad DSL or Cable
connection or even a faulty wire too.

But as for tracert's, never seen consistent below 10ms hops such as what
you're describing. Even on a T1 with hardly any traffic, never seen that
unless the hops are inter organization.

I think just the fact the connection is up or down is what's going on. Not
sure what the original poster's infrastructure contains, but maybe just
adding a small 4 port switch may just do the trick making DNS think it;s
always connected.


--
Regards,
Ace

Please direct all replies to the newsgroup so all can benefit.
This posting is provided "AS-IS" with no warranties and confers no
rights.

Ace Fekay, MCSE 2000, MCSE+I, MCSA, MCT, MVP
Microsoft Windows MVP - Active Directory
 
I remember seeing an article stating that if a DNS server is directly
connected to a cable modem or DSL modem that when the connection drops, then
the interface thinks it's down and causes the DNS service to hang and will
need to restart the DNS service, even if the connection comes back up. Now
if it's on a switch or hub, then the interface will always think that it's
"up" and the service won't drop out. I searched for the article, but cannot
find it... if I do, I'll post it.
Click to expand...

That's clearly not the GENERAL case (here, for instance) so
there must be other factors.

I have laptops that are DNS servers and they work just find
even after network outages, stand-by, or hibernation. Other
DNS servers on cable and DSL that just work, during and
after outages.

DNS is connectionless largely and even the TCP is intermittent
(disconnected after each request.)
 
In
That's clearly not the GENERAL case (here, for instance) so
there must be other factors.

I have laptops that are DNS servers and they work just find
even after network outages, stand-by, or hibernation. Other
DNS servers on cable and DSL that just work, during and
after outages.

DNS is connectionless largely and even the TCP is intermittent
(disconnected after each request.)
Click to expand...


Herb, like I said, if I find it, I'll post the article for you.

--
Regards,
Ace

Please direct all replies to the newsgroup so all can benefit.
This posting is provided "AS-IS" with no warranties and confers no
rights.

Ace Fekay, MCSE 2000, MCSE+I, MCSA, MCT, MVP
Microsoft Windows MVP - Active Directory
 
Thanks for the tips. ipconfig /renew does work as does
rebooting the router. I just wonder why it won't
automatically assign another ip address...
 
I'd love to see that article discussing DNS servers and
Cable modems. Let us know if you find it! Thanks
 
Jim said:
Thanks for the tips. ipconfig /renew does work as does
rebooting the router. I just wonder why it won't
automatically assign another ip address...
Click to expand...

If you turn that questio around backwards it may help
find the answer:

"Wonder why your machine doesn't automatically request
another address -- periodically?"

DHCP only assigns addresses to those who REQUEST
them. Your machine (DHCP client) is supposed to request
an address, and if no address is offered, re-try the request
periodically (every five minutes.)

BUT, if you machine HAS an address, then that address
BELONGS to that machine until the lease expires and their
is no reason to request a renewal until that time.

Think it through -- you will determine that most likely the
fault is with your cable modem, ISP, or whoever is LOSING
the leases on reboot or reconnection.

Your MACHINE owns that DHCP assigned address until
the lease expires but apparently your cable modem disagrees.

A simple script could be written -- and even run as a service --
to periodically check the connection and issue the renewal if
necessary.
 
In
Jim said:
Thanks for the tips. ipconfig /renew does work as does
rebooting the router. I just wonder why it won't
automatically assign another ip address...
Click to expand...


Ok, I'm now confused.....let me get this straight. You say you're running an
ipconfig /renew on the DNS server to get a new or refresh the IP address?

Now one of the strict requirements of DNS services is that a DNS server
needs to have a static IP. If the IP changes, then I can see why the service
has to be restarted, actually surprised it's running at all.

Or do I have your network description incorrect and assumed the wrong thing?
3

Do you have something like a LInksys or Netgear router in place connected to
the cable modem?

If so, is this LInksys or Netgear router running DHCP?

Is the DNS server in question a DHCP client, (not a statically configured
machine)?



Regards,
Ace

Please direct all replies to the newsgroup so all can benefit.
This posting is provided "AS-IS" with no warranties and confers no
rights.

Ace Fekay, MCSE 2000, MCSE+I, MCSA, MCT, MVP
Microsoft Windows MVP - Active Directory
 
Now one of the strict requirements of DNS services is that a DNS server
needs to have a static IP. If the IP changes, then I can see why the service
has to be restarted, actually surprised it's running at all.
Click to expand...

That's not really a strict requirement -- it's a requirement
on the interfaces that will be serviced, but many DNS
servers sit on routers, accepting requests on the inside
and servicing them through further requests on the external
network.

The only strict reason for a static address is that clients
must be able to find the DNS server by IP so if the address
the clients use changes then you will not find the DNS
server very useful (on that NIC.)

Read my answer in the thread above -- you will likely catch
on to his problem quickly....
 
In
Herb Martin said:
That's not really a strict requirement -- it's a requirement
on the interfaces that will be serviced, but many DNS
servers sit on routers, accepting requests on the inside
and servicing them through further requests on the external
network.

The only strict reason for a static address is that clients
must be able to find the DNS server by IP so if the address
the clients use changes then you will not find the DNS
server very useful (on that NIC.)

Read my answer in the thread above -- you will likely catch
on to his problem quickly....
Click to expand...

Well, one of the requirements of DNS is a static IP for proper
functionality. You're probably aware of this being familiar with the
courseware.

I see what you mean in your previous post. If the IP during that lease time
is being used by DNS, but when it changes, the DNS service needs to be
restarted to recognize the change and bind to that interface.



--
Regards,
Ace

Please direct all replies to the newsgroup so all can benefit.
This posting is provided "AS-IS" with no warranties and confers no
rights.

Ace Fekay, MCSE 2000, MCSE+I, MCSA, MCT, MVP
Microsoft Windows MVP - Active Directory
 
Well, one of the requirements of DNS is a static IP for proper
functionality. You're probably aware of this being familiar with the
courseware.
Click to expand...

If it says this in the courseware it's just silly -- we are talking about
multiple NICs. More likely it says, or at least means, static for the
NIC on which DNS will operate.

[One of the reasons I seldom use the courseware.]
I see what you mean in your previous post. If the IP during that lease time
is being used by DNS, but when it changes, the DNS service needs to be
restarted to recognize the change and bind to that interface.
Click to expand...

It's probably not even DNS (maybe) but rather somehow re-starting
DNS was causing the DHCP client to renew -- IF it's doing what
I believe seems fairly clear.

E.G.: He has a 2 day lease; the cable modem (or DHCP server) re-inits
and loses the lease. Now his address is invalid but he has a legitimate
right to keep using it -- and NO REASON to renew.

The tip-off hear is that renewing the DHCP lease fixes his problem without
having to restart DNS.
 
In
Herb Martin said:
Well, one of the requirements of DNS is a static IP for proper
functionality. You're probably aware of this being familiar with the
courseware.
Click to expand...

If it says this in the courseware it's just silly -- we are talking
about multiple NICs. More likely it says, or at least means, static
for the NIC on which DNS will operate.

[One of the reasons I seldom use the courseware.]
I see what you mean in your previous post. If the IP during that
lease time is being used by DNS, but when it changes, the DNS
service needs to be restarted to recognize the change and bind to
that interface.
Click to expand...

It's probably not even DNS (maybe) but rather somehow re-starting
DNS was causing the DHCP client to renew -- IF it's doing what
I believe seems fairly clear.

E.G.: He has a 2 day lease; the cable modem (or DHCP server) re-inits
and loses the lease. Now his address is invalid but he has a
legitimate right to keep using it -- and NO REASON to renew.

The tip-off hear is that renewing the DHCP lease fixes his problem
without having to restart DNS.
Click to expand...


I agree that renewing the lease will fix it instead of restarting DNS, since
it only makes sense, and at that point, DNS will bind to that interface. AS
for the courseware, it loosely says it's a requirement, after all, you even
stated, we should have a consistent address for DNS to sit on for others to
be able to use the machine. Sure there are errors in the courseware, but
they work themselves out thru the trainers submitting errors to the error
log which we usually check for an update or thru our private MCT newsgroup.
So the courseware is good to use.



--
Regards,
Ace

Please direct all replies to the newsgroup so all can benefit.
This posting is provided "AS-IS" with no warranties and confers no
rights.

Ace Fekay, MCSE 2000, MCSE+I, MCSA, MCT, MVP
Microsoft Windows MVP - Active Directory
 
I agree that renewing the lease will fix it instead of restarting DNS,
since
it only makes sense, and at that point, DNS will bind to that interface. AS
for the courseware, it loosely says it's a requirement, after all, you even
stated, we should have a consistent address for DNS to sit on for others to
be able to use the machine.
Click to expand...

That's what I indicated to you originally -- so really the
courseware (based on what you say above) doesn't address
the issue of multiple NICs.

And if you think it through a bit there could even be NICs that
don't support DNS -- the only thing the courseware (likely) refers
to is those NICs which will answer DNS queries.

There is NOTHING wrong with using a dynamic address for the
DNS server to forward requests, perform actual recursion itself,or
for other purposes than DNS.

It just won't "serve" on those dynamic IPs -- it actually can do that,
but it doesn't make much sense.

This guys problem is likely that his ISP is invalidating a LEGITIMATE
lease before it expires and then telling him that it is "his problem."
Sure there are errors in the courseware, but
they work themselves out thru the trainers submitting errors to the error
log which we usually check for an update or thru our private MCT
Click to expand...
newsgroup.

It's not that useful to use them blindly as a "reference" however.



--
Herb Martin
"Ace Fekay [MVP]"
In Herb Martin <[email protected]> posted their thoughts, then I offered mine
Well, one of the requirements of DNS is a static IP for proper
functionality. You're probably aware of this being familiar with the
courseware.
Click to expand...

If it says this in the courseware it's just silly -- we are talking
about multiple NICs. More likely it says, or at least means, static
for the NIC on which DNS will operate.

[One of the reasons I seldom use the courseware.]
I see what you mean in your previous post. If the IP during that
lease time is being used by DNS, but when it changes, the DNS
service needs to be restarted to recognize the change and bind to
that interface.
Click to expand...

It's probably not even DNS (maybe) but rather somehow re-starting
DNS was causing the DHCP client to renew -- IF it's doing what
I believe seems fairly clear.

E.G.: He has a 2 day lease; the cable modem (or DHCP server) re-inits
and loses the lease. Now his address is invalid but he has a
legitimate right to keep using it -- and NO REASON to renew.

The tip-off hear is that renewing the DHCP lease fixes his problem
without having to restart DNS.
Click to expand...


I agree that renewing the lease will fix it instead of restarting DNS, since
it only makes sense, and at that point, DNS will bind to that interface. AS
for the courseware, it loosely says it's a requirement, after all, you even
stated, we should have a consistent address for DNS to sit on for others to
be able to use the machine. Sure there are errors in the courseware, but
they work themselves out thru the trainers submitting errors to the error
log which we usually check for an update or thru our private MCT newsgroup.
So the courseware is good to use.



--
Regards,
Ace

Please direct all replies to the newsgroup so all can benefit.
This posting is provided "AS-IS" with no warranties and confers no
rights.

Ace Fekay, MCSE 2000, MCSE+I, MCSA, MCT, MVP
Microsoft Windows MVP - Active Directory
Click to expand...
 
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