Windows Name Resolution With Double Backslash

Can someone point me to an article that explains the algorithm that Windows
goes through when trying to resolve a name that uses the UNC convention
\\myserver\sharename? I'm hoping that understanding how that algorithm
differs from an nslookup will help me to solve a name resolution problem I
am having.

The problem I am having is that nslookup resolves both the host and the
domain, but when the host and domain are placed into a UNC then Windows says
the network location cannot be reached. Specifically:

- myserver is the only domain controller in forest my.domain.com and has IP
172.1.1.1
- myserver.my.domain.com, myserver, and my.domain.com all resolve fine as
arguments to nslookup, to the IP 172.1.1.1
- The command line "dir \\myserver\sysvol" works fine.
- The command line "dir \\172.1.1.1.\sysvol" works fine. This is a big
clue given the next two symptoms:
- The command line "dir \\myserver.my.domain.com\sysvol" FAILS with network
location cannot be reached.
- The command line "dir \\my.domain.com\sysvol" FAILS with network location
cannot be reached.

Neither dcdiag /v nor netdiag /v show any real failures in DNS. But the
above symptoms to me clearly suggest a problem in name resolution for the
UNC when used with DNS names. The UNC convention will work fine with
either an IP or a simple host name. This to me suggests that the failure
is somewhere in the name lookup algorithm for UNC names, at the point it
turns to use of the DNS server. If anyone has a clue on this I would
appreciate a tip on what to investigate.

--
Will

In news:xKmdnVWBWsJTvxDeRVn-(E-Mail Removed),
Will <westes-(E-Mail Removed)> typed:
> Can someone point me to an article that explains the algorithm that
> Windows goes through when trying to resolve a name that uses the UNC
> convention \\myserver\sharename? I'm hoping that understanding how
> that algorithm differs from an nslookup will help me to solve a name
> resolution problem I am having.
>
> The problem I am having is that nslookup resolves both the host and
> the domain, but when the host and domain are placed into a UNC then
> Windows says the network location cannot be reached. Specifically:
>
> - myserver is the only domain controller in forest my.domain.com and
> has IP 172.1.1.1
> - myserver.my.domain.com, myserver, and my.domain.com all resolve
> fine as arguments to nslookup, to the IP 172.1.1.1
> - The command line "dir \\myserver\sysvol" works fine.
> - The command line "dir \\172.1.1.1.\sysvol" works fine. This is a
> big clue given the next two symptoms:
> - The command line "dir \\myserver.my.domain.com\sysvol" FAILS with
> network location cannot be reached.
> - The command line "dir \\my.domain.com\sysvol" FAILS with network
> location cannot be reached.
>
> Neither dcdiag /v nor netdiag /v show any real failures in DNS.
> But the above symptoms to me clearly suggest a problem in name
> resolution for the UNC when used with DNS names. The UNC convention
> will work fine with either an IP or a simple host name. This to me
> suggests that the failure is somewhere in the name lookup algorithm
> for UNC names, at the point it turns to use of the DNS server. If
> anyone has a clue on this I would appreciate a tip on what to
> investigate.

Post an ipconfig /all from the server & a client.

I found the problem. Windows has a group policy dependency on TCP/IP
NetBIOS Helper service, even when NetBIOS is disabled for the interface.
Surprising.

--
Will


"Lanwench [MVP - Exchange]"
<(E-Mail Removed) ahoo.com> wrote in message
news:(E-Mail Removed)...
> In news:xKmdnVWBWsJTvxDeRVn-(E-Mail Removed),
> Will <westes-(E-Mail Removed)> typed:
> > Can someone point me to an article that explains the algorithm that
> > Windows goes through when trying to resolve a name that uses the UNC
> > convention \\myserver\sharename? I'm hoping that understanding how
> > that algorithm differs from an nslookup will help me to solve a name
> > resolution problem I am having.
> >
> > The problem I am having is that nslookup resolves both the host and
> > the domain, but when the host and domain are placed into a UNC then
> > Windows says the network location cannot be reached. Specifically:
> >
> > - myserver is the only domain controller in forest my.domain.com and
> > has IP 172.1.1.1
> > - myserver.my.domain.com, myserver, and my.domain.com all resolve
> > fine as arguments to nslookup, to the IP 172.1.1.1
> > - The command line "dir \\myserver\sysvol" works fine.
> > - The command line "dir \\172.1.1.1.\sysvol" works fine. This is a
> > big clue given the next two symptoms:
> > - The command line "dir \\myserver.my.domain.com\sysvol" FAILS with
> > network location cannot be reached.
> > - The command line "dir \\my.domain.com\sysvol" FAILS with network
> > location cannot be reached.
> >
> > Neither dcdiag /v nor netdiag /v show any real failures in DNS.
> > But the above symptoms to me clearly suggest a problem in name
> > resolution for the UNC when used with DNS names. The UNC convention
> > will work fine with either an IP or a simple host name. This to me
> > suggests that the failure is somewhere in the name lookup algorithm
> > for UNC names, at the point it turns to use of the DNS server. If
> > anyone has a clue on this I would appreciate a tip on what to
> > investigate.
>
> Post an ipconfig /all from the server & a client.
>
>