Dynamic DNS (Netmask Ordering)

[Jamie]

On our primary DNS server, we use netmask ordering, so one host name
can be used arocc multiple IP addresses.

For instance we have an FTP server with the following entries:

192.168.1.1
192.168.2.1
192.168.3.1

So when a host looks for 'ftp.domainname.com' the response will come
back based on the subnet that the client is on.

This works well, but we have a VPN in where our assigned IP address is
192.168.4.xxx

When we resolve 'ftp.domainname.com' it will come back randomly between
all three of the host IP's we have entered, becasue we are not on any
of those subnets.

How can I make 'ftp.domainname.com' resolve only to 192.168.1.1 when
clients are on the 192.168.4.xxx subnet?

 

[Herb Martin]

On our primary DNS server, we use netmask ordering, so one host name
can be used arocc multiple IP addresses.

For instance we have an FTP server with the following entries:

192.168.1.1
192.168.2.1
192.168.3.1

So when a host looks for 'ftp.domainname.com' the response will come
back based on the subnet that the client is on.

This works well, but we have a VPN in where our assigned IP address is
192.168.4.xxx

When we resolve 'ftp.domainname.com' it will come back randomly between
all three of the host IP's we have entered, becasue we are not on any
of those subnets.

That is the expected (default) behavior.)

How can I make 'ftp.domainname.com' resolve only to 192.168.1.1 when
clients are on the 192.168.4.xxx subnet?

In your specific example you can turn OFF "round robin"
(leave Netmask Ordering enabled) and ensure that the
1.1 address is FIRST in the file.

Round robin is the feature that is randomizing the return
when there is no best netmask ordering match.

(It's located in the advanced settings near to the netmask
ordering checkbox.)

 

[MWood]

Hi,

Working on the same issue here and essentially have it working, except
one problem.

I've setup an entry named "example" so I resolve to
example.domainname.com using the subnet the computer is on. The
problem is that it's not always working. When pinging just "example" I
get the correct subnet, but when adding the domainname.com it
occasionally resolves to a different subnet.


Any help is appreciated.

thanks

Mark

On our primary DNS server, we use netmask ordering, so one host name
can be used arocc multiple IP addresses.

For instance we have an FTP server with the following entries:

192.168.1.1
192.168.2.1
192.168.3.1

So when a host looks for 'ftp.domainname.com' the response will come
back based on the subnet that the client is on.

This works well, but we have a VPN in where our assigned IP address is
192.168.4.xxx

When we resolve 'ftp.domainname.com' it will come back randomly between
all three of the host IP's we have entered, becasue we are not on any
of those subnets.

That is the expected (default) behavior.)

How can I make 'ftp.domainname.com' resolve only to 192.168.1.1 when
clients are on the 192.168.4.xxx subnet?

In your specific example you can turn OFF "round robin"
(leave Netmask Ordering enabled) and ensure that the
1.1 address is FIRST in the file.

Round robin is the feature that is randomizing the return
when there is no best netmask ordering match.

(It's located in the advanced settings near to the netmask
ordering checkbox.)

--
Herb Martin, MCSE, MVP
Accelerated MCSE
http://www.LearnQuick.Com
[phone number on web site]

 

[Herb Martin]

Hi,

Working on the same issue here and essentially have it working, except
one problem.

I've setup an entry named "example" so I resolve to
example.domainname.com using the subnet the computer is on. The
problem is that it's not always working. When pinging just "example" I
get the correct subnet, but when adding the domainname.com it
occasionally resolves to a different subnet.

Assuming you are resolving the same name there is NO
difference between those methods as far as the DNS
SERVER is concerned.

[If however, you end up resolving through NetBIOS either
Broadcasts or WINS requests might give a different result.]

Ping uses Hosts file then DNS so if DNS resolution is used
the name will be the same one whether you type in example
or example.domainname.com as long as you aren't resolving
a name from another domain which just HAPPENS to have
"example" in it -- for the latter to happen you would likely
need to have implemented checking parent suffixes OR
checking additional DNS name suffixes.

But all of this is CLIENT only and has nothing to do with
the DNS server.

The DNS server will only return answers for the Fully
Qualified names the client software actually requests.

The feature of appending suffixes is a purely a client
feature to allow you to avoid typing.

--
Herb Martin, MCSE, MVP
Accelerated MCSE
http://www.LearnQuick.Com
[phone number on web site]

Any help is appreciated.

thanks

Mark

On our primary DNS server, we use netmask ordering, so one host name
can be used arocc multiple IP addresses.

For instance we have an FTP server with the following entries:

192.168.1.1
192.168.2.1
192.168.3.1

So when a host looks for 'ftp.domainname.com' the response will come
back based on the subnet that the client is on.

This works well, but we have a VPN in where our assigned IP address is
192.168.4.xxx

When we resolve 'ftp.domainname.com' it will come back randomly between
all three of the host IP's we have entered, becasue we are not on any
of those subnets.

That is the expected (default) behavior.)

How can I make 'ftp.domainname.com' resolve only to 192.168.1.1 when
clients are on the 192.168.4.xxx subnet?

In your specific example you can turn OFF "round robin"
(leave Netmask Ordering enabled) and ensure that the
1.1 address is FIRST in the file.

Round robin is the feature that is randomizing the return
when there is no best netmask ordering match.

(It's located in the advanced settings near to the netmask
ordering checkbox.)

--
Herb Martin, MCSE, MVP
Accelerated MCSE
http://www.LearnQuick.Com
[phone number on web site]