Can't Ping DNS Server

[Rick]

having a weird issue on our LAN, We have a vlan setup with 6 machines
and every 3 days or so they drop off of the LAN only because they can
ping everything but the DNS server. If I go to the DNS server and ping
one of the machines it comes back and I'm able to Ping the DNS server.

I'm lost as to what might be happening

Thanks in advance

Rick

 

[Ace Fekay [MVP]]

In

having a weird issue on our LAN, We have a vlan setup with 6 machines
and every 3 days or so they drop off of the LAN only because they can
ping everything but the DNS server. If I go to the DNS server and ping
one of the machines it comes back and I'm able to Ping the DNS server.

I'm lost as to what might be happening

Thanks in advance

Rick

That's a tough one and with VLANs and their mutliple configuration options,
it is truly difficult to diagnose. One reason I really hate VLANs but when
we need them, such as controlling wireless access, we try to minimize their
use.

One thing I remember is if the interface that DNS is listening on goes to
sleep, so will the DNS service. By the mere fact that you ping from it wakes
it up, kind of makes me hint towards that direction.

--
Ace
Innovative IT Concepts, Inc (IITCI)
Willow Grove, PA

This posting is provided "AS-IS" with no warranties or guarantees and
confers no rights.

Ace Fekay, MCSE 2003 & 2000, MCSA 2003 & 2000, MCSE+I, MCT, MVP
Microsoft MVP - Directory Services
Microsoft Certified Trainer

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[Rick]

Ace,

thanks for the reply, we are still trying to figure out this one.

Rick

 

[Ace Fekay [MVP]]

In

Ace,

thanks for the reply, we are still trying to figure out this one.

Rick

Let me know if you do and what it was, that is unless anyone else comes up
with a solution.

Ace

 

[Ryan Hanisco]

This could be something with the ARP or CAM tables. The infrastructure
equipment will let the record time out and then the switch cannot find
its destination without doing a port flood to find the device.

If you are using VLANs and are routing between your workstations and the
DNS server, you might look at an IP helper-address entry pointing at the
server. Otherwise, you will have to go a bit deeper into the problem.

Let us know what your network looks like and what equipment you are
using and we'll get it.

Ryan Hanisco
FlagShip Integration Services

 

[Kurt]

In

That's a tough one and with VLANs and their mutliple configuration options,
it is truly difficult to diagnose. One reason I really hate VLANs but when
we need them, such as controlling wireless access, we try to minimize their
use.

One thing I remember is if the interface that DNS is listening on goes to
sleep, so will the DNS service. By the mere fact that you ping from it wakes
it up, kind of makes me hint towards that direction.

Listen to Ace on this. Make sure your network card is not being disabled
in your power options. Even with "wake-on LAN", if you have it connected
to a managed switch with spanning-tree enabled (especially a Cisco), the
port may take so long to begin forwarding that the requests time out.
Set all of the ports on your switch to "spanning-tree portfast" or the
equivalent for whatever brand of switch you use.

....kurt