Re: DHCP, DNS, NETBIOS and WINS

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• In reply to: JohnDeeze: "DHCP, DNS, NETBIOS and WINS"
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Date: Sun, 12 Dec 2004 15:52:06 +1100

"JohnDeeze" <JohnDeeze@discussions.microsoft.com> wrote in message
news:F0A8B7E2-E766-44EE-8FB2-C4F83FE2130D@microsoft.com...
>I am new to networking, although i am helping administer a network and
>would
> like someone to explain the following to me:
>
> I believe the following to be an accurate picture of Windows networks.
>
> NETBIOS - Is the Name of the PC e.g. (PC1)
>
> DNS resolves the IP address of the PC against a pc's name, therefore if i
> ping PC1 it will return reply from PC1 and give me its IP address.
>
> Reverse DNS resolves the IP address of a PC to the NETBIOS/DNS name,
> therefore if i ping 10.1.1.1 it will return the name of the PC e.g. PC1.
>
> WINS resolves the name of the PC for older pc's like Win NT and Windows 98
> as DNS was not in play or DNS has since taken over WINS duites
>
> DHCP assigns an available IP address to a PC which logs onto the network,
> provided the pc has "obtain an IP address automatially" in its network
> TCP/IP
> options.
>
> Question 1 - Why not just do away with WINS as 98/NT have DNS options in
> their network TCP/IP properties. Why did we need WINS?
>
> Question 2 - On an NT/98 PC do i need to insert a DNS server address in
> TCP/IP properties box if i have those PC's WINS server properties in
> netowrk
> TP/IP pointing to the WINS server?
>
> Quesrion 3 - Why is there an option saying use NETBIOS over TCP/IP in
> network card properties?
>
> Question 4 - Why do we require reverse DNS?
>
> Question 5 - If the name of the PC sits on the DNS server do we still use
> NETBIOS
>
> Any help assistance greatly appreciated

  Your general description is not really accurate. Here is a very
abbreviated history.

    Microsoft has been using Netbios names since before Windows. The Netbios
namespace is a "flat" namespace, so the same name cannot be reused.
DOS/Windows originally used a proprietary (non-routable) protocol called
Netbeui, and this was adapted to use IP addresses with Netbios over TCP/IP.
Netbios names were resolved by LAN broadcasts. To "see" a machine on a
different segment, you needed to use an LMHOSTS file to resolve its name to
its IP address. To automate the process, WINS was developed. WINS allows
machines to register their Netbios names and IP addresses in the WINS
database. Any machine which can contact WINS can resolve the Netbios name of
a registered computer to its IP address.

    DNS is an heirarchical database. Names can be reused as long as they are
not in the same DNS zone. machine.z1.company.local is not the same machine
as machine.z2.company.local . The DNS name (without the DNS suffix) does not
have to be the same as the Netbios name, but usually it is. That is why, in
a simple network, you can resolve a machine name to its IP address using
either DNS or WINS. DNS has traditionally been used in UNIX and to power the
name resolution of the Internet.

    Before Windows 2000, Microsoft OSs used Netbios names as their basic
naming service. Services such as netlogon and the browser service used
special Netbios names. NT and W9x clients found these services by broadcast
or from WINS. DNS was not required for ordinary Microsoft networking, but
was available for if required for other purposes (such as Internet access).

    W2k and later systems rely on Active Directory. This was a major
departure for Microsoft, as AD depends on DNS. This is fine for W2k/XP
clients, but legacy clients like W9x and NT were built to use Netbios. Even
if DNS is configured correctly on these machines, they may require WINS to
find certain resources because the are programmed to use the Netbios name,
not DNS.

Q1. You need WINS for legacy clients because they were not designed to use
DNS.

Q2. You do not really need DNS settings (for local names) on legacy systems
if WINS is configured. But you certainly do to get access to the Internet.

Q3. Netbios over TCP/IP is optional because some W2k/W2k3/XP systems running
AD do not need it at all. In that case, you can disable it and save some LAN
traffic.

Q4. The DNS lookup process is very simple. Given a name, it will search for
it in the zone database and return an IP address. To do the reverse process
(provide an IP and get back a name) you need a reverse lookup zone. Have you
tried looking up a phone number in an alphabetic white pages?

Q5. For legacy systems, yes. For W2k/XP maybe. It depends on what they are
doing. Some older programs may have Netbios calls hard-coded into the app.
These will fail without Netbt.

• Previous message: Roger Abell: "Re: WebServer behind firewall"
• In reply to: JohnDeeze: "DHCP, DNS, NETBIOS and WINS"
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