Dns.GetHostEntry functionality

[David]

I have this code:

try
{
IPAddress[] addresses =
Dns.GetHostEntry("david-1").AddressList;
foreach (IPAddress address in addresses)
{
if (address.AddressFamily == AddressFamily.InterNetwork)
{
m_strServeIP = address.ToString();
break;
}
}
}
catch (SocketException ex)
{
MessageBox.Show(ex.Message);
Close();
return;
}

A SocketException is thrown "No such host is known".

Yet, I know I have connectivity since I can browse the internet and I have a
valid ip address and it can be pinged from the david-1 computer. My DHCP
server is giving out dns and gateway information. Why does the GetHostEntry
fail?

 

[Paul G. Tobey [eMVP]]

The only thing that I can think of is that the name you're asking for is
wrong (isn't the real device name), or that there's a bug in resolution for
NetBIOS names with - characters in them. What sort of device are we talking
about (it's not Windows Mobile, for example?)? Version of CE? Networking
components built in?

Your code works fine on my device.

Paul T.

 

[David]

HP 2790
Windows Mobile 5.0
HP iPAQ Wi-Fi Adapter

I have OpenNetCF installed on the device and I have used it to build some
code to go through the network configuration. It shows that I have the
correct DNS entries.

"Paul G. Tobey [eMVP]" <p space tobey no spam AT no instrument no spam DOT
com> wrote in message news:[email protected]...

The only thing that I can think of is that the name you're asking for is
wrong (isn't the real device name), or that there's a bug in resolution
for NetBIOS names with - characters in them. What sort of device are we
talking about (it's not Windows Mobile, for example?)? Version of CE?
Networking components built in?

Your code works fine on my device.

Paul T.

I have this code:

try
{
IPAddress[] addresses =
Dns.GetHostEntry("david-1").AddressList;
foreach (IPAddress address in addresses)
{
if (address.AddressFamily ==
AddressFamily.InterNetwork)
{
m_strServeIP = address.ToString();
break;
}
}
}
catch (SocketException ex)
{
MessageBox.Show(ex.Message);
Close();
return;
}

A SocketException is thrown "No such host is known".

Yet, I know I have connectivity since I can browse the internet and I
have a valid ip address and it can be pinged from the david-1 computer.
My DHCP server is giving out dns and gateway information. Why does the
GetHostEntry fail?

 

[David]

david-1 is a PC running Windows Vista.

"Paul G. Tobey [eMVP]" <p space tobey no spam AT no instrument no spam DOT
com> wrote in message news:[email protected]...

The only thing that I can think of is that the name you're asking for is
wrong (isn't the real device name), or that there's a bug in resolution
for NetBIOS names with - characters in them. What sort of device are we
talking about (it's not Windows Mobile, for example?)? Version of CE?
Networking components built in?

Your code works fine on my device.

Paul T.

I have this code:

try
{
IPAddress[] addresses =
Dns.GetHostEntry("david-1").AddressList;
foreach (IPAddress address in addresses)
{
if (address.AddressFamily ==
AddressFamily.InterNetwork)
{
m_strServeIP = address.ToString();
break;
}
}
}
catch (SocketException ex)
{
MessageBox.Show(ex.Message);
Close();
return;
}

A SocketException is thrown "No such host is known".

Yet, I know I have connectivity since I can browse the internet and I
have a valid ip address and it can be pinged from the david-1 computer.
My DHCP server is giving out dns and gateway information. Why does the
GetHostEntry fail?

 

[Paul G. Tobey [eMVP]]

DNS isn't being used to resolve some local name. DNS is what is used to
resolve things like www.microsoft.com. There's no local service that knows
about your PC's NetBIOS name. I'm not 100% sure that NetBIOS names like
that *should* be resolved on WM5 devices. Unfortunately, I also can't check
it right now on mine. Maybe someone else knows...

Paul T.

HP 2790
Windows Mobile 5.0
HP iPAQ Wi-Fi Adapter

I have OpenNetCF installed on the device and I have used it to build some
code to go through the network configuration. It shows that I have the
correct DNS entries.

"Paul G. Tobey [eMVP]" <p space tobey no spam AT no instrument no spam DOT
com> wrote in message news:[email protected]...

The only thing that I can think of is that the name you're asking for is
wrong (isn't the real device name), or that there's a bug in resolution
for NetBIOS names with - characters in them. What sort of device are we
talking about (it's not Windows Mobile, for example?)? Version of CE?
Networking components built in?

Your code works fine on my device.

Paul T.

I have this code:

try
{
IPAddress[] addresses =
Dns.GetHostEntry("david-1").AddressList;
foreach (IPAddress address in addresses)
{
if (address.AddressFamily ==
AddressFamily.InterNetwork)
{
m_strServeIP = address.ToString();
break;
}
}
}
catch (SocketException ex)
{
MessageBox.Show(ex.Message);
Close();
return;
}

A SocketException is thrown "No such host is known".

Yet, I know I have connectivity since I can browse the internet and I
have a valid ip address and it can be pinged from the david-1 computer.
My DHCP server is giving out dns and gateway information. Why does the
GetHostEntry fail?

 

[David]

If I substitute 10.0.0.20 for david-1, everything works fine. That is, the
functionality of my app works to connect to the PC and retrieve data and
send data. So this tells me that I have connectivity to the network. It is
just that DNS seems not work work. Does Vista not use netbios names? I am
pretty sure that it does.

"Paul G. Tobey [eMVP]" <p space tobey no spam AT no instrument no spam DOT
com> wrote in message news:[email protected]...

The only thing that I can think of is that the name you're asking for is
wrong (isn't the real device name), or that there's a bug in resolution
for NetBIOS names with - characters in them. What sort of device are we
talking about (it's not Windows Mobile, for example?)? Version of CE?
Networking components built in?

Your code works fine on my device.

Paul T.

I have this code:

try
{
IPAddress[] addresses =
Dns.GetHostEntry("david-1").AddressList;
foreach (IPAddress address in addresses)
{
if (address.AddressFamily ==
AddressFamily.InterNetwork)
{
m_strServeIP = address.ToString();
break;
}
}
}
catch (SocketException ex)
{
MessageBox.Show(ex.Message);
Close();
return;
}

A SocketException is thrown "No such host is known".

Yet, I know I have connectivity since I can browse the internet and I
have a valid ip address and it can be pinged from the david-1 computer.
My DHCP server is giving out dns and gateway information. Why does the
GetHostEntry fail?

 

[Paul G. Tobey [eMVP]]

Hmmm. Well, I can't test that. Is the NetBIOS protocol enabled for the
network adapter that 'faces' your WM5 device?

Paul T.

david-1 is a PC running Windows Vista.

"Paul G. Tobey [eMVP]" <p space tobey no spam AT no instrument no spam DOT
com> wrote in message news:[email protected]...

The only thing that I can think of is that the name you're asking for is
wrong (isn't the real device name), or that there's a bug in resolution
for NetBIOS names with - characters in them. What sort of device are we
talking about (it's not Windows Mobile, for example?)? Version of CE?
Networking components built in?

Your code works fine on my device.

Paul T.

I have this code:

try
{
IPAddress[] addresses =
Dns.GetHostEntry("david-1").AddressList;
foreach (IPAddress address in addresses)
{
if (address.AddressFamily ==
AddressFamily.InterNetwork)
{
m_strServeIP = address.ToString();
break;
}
}
}
catch (SocketException ex)
{
MessageBox.Show(ex.Message);
Close();
return;
}

A SocketException is thrown "No such host is known".

Yet, I know I have connectivity since I can browse the internet and I
have a valid ip address and it can be pinged from the david-1 computer.
My DHCP server is giving out dns and gateway information. Why does the
GetHostEntry fail?

 

[David]

DNS is absolutely used to resolve computer names. It is also used to resolve
names on the internet too.

"Paul G. Tobey [eMVP]" <p space tobey no spam AT no instrument no spam DOT
com> wrote in message news:[email protected]...

DNS isn't being used to resolve some local name. DNS is what is used to
resolve things like www.microsoft.com. There's no local service that
knows about your PC's NetBIOS name. I'm not 100% sure that NetBIOS names
like that *should* be resolved on WM5 devices. Unfortunately, I also
can't check it right now on mine. Maybe someone else knows...

Paul T.

HP 2790
Windows Mobile 5.0
HP iPAQ Wi-Fi Adapter

I have OpenNetCF installed on the device and I have used it to build some
code to go through the network configuration. It shows that I have the
correct DNS entries.

"Paul G. Tobey [eMVP]" <p space tobey no spam AT no instrument no spam
DOT com> wrote in message news:[email protected]...

The only thing that I can think of is that the name you're asking for is
wrong (isn't the real device name), or that there's a bug in resolution
for NetBIOS names with - characters in them. What sort of device are we
talking about (it's not Windows Mobile, for example?)? Version of CE?
Networking components built in?

Your code works fine on my device.

Paul T.

I have this code:

try
{
IPAddress[] addresses =
Dns.GetHostEntry("david-1").AddressList;
foreach (IPAddress address in addresses)
{
if (address.AddressFamily ==
AddressFamily.InterNetwork)
{
m_strServeIP = address.ToString();
break;
}
}
}
catch (SocketException ex)
{
MessageBox.Show(ex.Message);
Close();
return;
}

A SocketException is thrown "No such host is known".

Yet, I know I have connectivity since I can browse the internet and I
have a valid ip address and it can be pinged from the david-1 computer.
My DHCP server is giving out dns and gateway information. Why does the
GetHostEntry fail?

 

[David]

Where do I check that?

"Paul G. Tobey [eMVP]" <p space tobey no spam AT no instrument no spam DOT
com> wrote in message news:[email protected]...

Hmmm. Well, I can't test that. Is the NetBIOS protocol enabled for the
network adapter that 'faces' your WM5 device?

Paul T.

david-1 is a PC running Windows Vista.

"Paul G. Tobey [eMVP]" <p space tobey no spam AT no instrument no spam
DOT com> wrote in message news:[email protected]...

The only thing that I can think of is that the name you're asking for is
wrong (isn't the real device name), or that there's a bug in resolution
for NetBIOS names with - characters in them. What sort of device are we
talking about (it's not Windows Mobile, for example?)? Version of CE?
Networking components built in?

Your code works fine on my device.

Paul T.

I have this code:

try
{
IPAddress[] addresses =
Dns.GetHostEntry("david-1").AddressList;
foreach (IPAddress address in addresses)
{
if (address.AddressFamily ==
AddressFamily.InterNetwork)
{
m_strServeIP = address.ToString();
break;
}
}
}
catch (SocketException ex)
{
MessageBox.Show(ex.Message);
Close();
return;
}

A SocketException is thrown "No such host is known".

Yet, I know I have connectivity since I can browse the internet and I
have a valid ip address and it can be pinged from the david-1 computer.
My DHCP server is giving out dns and gateway information. Why does the
GetHostEntry fail?

 

[David]

If you mean, is NetBIOS enabled on my Vista computer, then yes, it is
enabled.

Where do I check that?

"Paul G. Tobey [eMVP]" <p space tobey no spam AT no instrument no spam DOT
com> wrote in message news:[email protected]...

Hmmm. Well, I can't test that. Is the NetBIOS protocol enabled for the
network adapter that 'faces' your WM5 device?

Paul T.

david-1 is a PC running Windows Vista.

"Paul G. Tobey [eMVP]" <p space tobey no spam AT no instrument no spam
DOT com> wrote in message The only thing that I can think of is that the name you're asking for
is wrong (isn't the real device name), or that there's a bug in
resolution for NetBIOS names with - characters in them. What sort of
device are we talking about (it's not Windows Mobile, for example?)?
Version of CE? Networking components built in?

Your code works fine on my device.

Paul T.

I have this code:

try
{
IPAddress[] addresses =
Dns.GetHostEntry("david-1").AddressList;
foreach (IPAddress address in addresses)
{
if (address.AddressFamily ==
AddressFamily.InterNetwork)
{
m_strServeIP = address.ToString();
break;
}
}
}
catch (SocketException ex)
{
MessageBox.Show(ex.Message);
Close();
return;
}

A SocketException is thrown "No such host is known".

Yet, I know I have connectivity since I can browse the internet and I
have a valid ip address and it can be pinged from the david-1
computer. My DHCP server is giving out dns and gateway information.
Why does the GetHostEntry fail?

 

[Paul G. Tobey [eMVP]]

It could be used to resolve your local names, but only if those names are
stored on some local or corporate DNS server. Generally, that's not the
case in an office environment. For example, here, in my office, you can be
100% sure that DNS is not resolving the name of my machine, "FARSIDE". I've
watched the packets...

Paul T.

DNS is absolutely used to resolve computer names. It is also used to
resolve names on the internet too.

"Paul G. Tobey [eMVP]" <p space tobey no spam AT no instrument no spam DOT
com> wrote in message news:[email protected]...

DNS isn't being used to resolve some local name. DNS is what is used to
resolve things like www.microsoft.com. There's no local service that
knows about your PC's NetBIOS name. I'm not 100% sure that NetBIOS names
like that *should* be resolved on WM5 devices. Unfortunately, I also
can't check it right now on mine. Maybe someone else knows...

Paul T.

HP 2790
Windows Mobile 5.0
HP iPAQ Wi-Fi Adapter

I have OpenNetCF installed on the device and I have used it to build
some code to go through the network configuration. It shows that I have
the correct DNS entries.

"Paul G. Tobey [eMVP]" <p space tobey no spam AT no instrument no spam
DOT com> wrote in message The only thing that I can think of is that the name you're asking for
is wrong (isn't the real device name), or that there's a bug in
resolution for NetBIOS names with - characters in them. What sort of
device are we talking about (it's not Windows Mobile, for example?)?
Version of CE? Networking components built in?

Your code works fine on my device.

Paul T.

I have this code:

try
{
IPAddress[] addresses =
Dns.GetHostEntry("david-1").AddressList;
foreach (IPAddress address in addresses)
{
if (address.AddressFamily ==
AddressFamily.InterNetwork)
{
m_strServeIP = address.ToString();
break;
}
}
}
catch (SocketException ex)
{
MessageBox.Show(ex.Message);
Close();
return;
}

A SocketException is thrown "No such host is known".

Yet, I know I have connectivity since I can browse the internet and I
have a valid ip address and it can be pinged from the david-1
computer. My DHCP server is giving out dns and gateway information.
Why does the GetHostEntry fail?

 

[Paul G. Tobey [eMVP]]

I'm no Vista expert. Try resolving www.microsoft.com. I'm pretty sure that
will work.

Paul T.

If I substitute 10.0.0.20 for david-1, everything works fine. That is, the
functionality of my app works to connect to the PC and retrieve data and
send data. So this tells me that I have connectivity to the network. It is
just that DNS seems not work work. Does Vista not use netbios names? I am
pretty sure that it does.

"Paul G. Tobey [eMVP]" <p space tobey no spam AT no instrument no spam DOT
com> wrote in message news:[email protected]...

The only thing that I can think of is that the name you're asking for is
wrong (isn't the real device name), or that there's a bug in resolution
for NetBIOS names with - characters in them. What sort of device are we
talking about (it's not Windows Mobile, for example?)? Version of CE?
Networking components built in?

Your code works fine on my device.

Paul T.

I have this code:

try
{
IPAddress[] addresses =
Dns.GetHostEntry("david-1").AddressList;
foreach (IPAddress address in addresses)
{
if (address.AddressFamily ==
AddressFamily.InterNetwork)
{
m_strServeIP = address.ToString();
break;
}
}
}
catch (SocketException ex)
{
MessageBox.Show(ex.Message);
Close();
return;
}

A SocketException is thrown "No such host is known".

Yet, I know I have connectivity since I can browse the internet and I
have a valid ip address and it can be pinged from the david-1 computer.
My DHCP server is giving out dns and gateway information. Why does the
GetHostEntry fail?

 

[David]

Ok, I can buy into that. However, I work from home and my network resolves
the name requests through my Windows Server 2008 system.

Just curious, in a network like your office network, where do the names get
resolved?

"Paul G. Tobey [eMVP]" <p space tobey no spam AT no instrument no spam DOT
com> wrote in message news:[email protected]...

I'm no Vista expert. Try resolving www.microsoft.com. I'm pretty sure
that will work.

Paul T.

If I substitute 10.0.0.20 for david-1, everything works fine. That is,
the functionality of my app works to connect to the PC and retrieve data
and send data. So this tells me that I have connectivity to the network.
It is just that DNS seems not work work. Does Vista not use netbios
names? I am pretty sure that it does.

"Paul G. Tobey [eMVP]" <p space tobey no spam AT no instrument no spam
DOT com> wrote in message news:[email protected]...

The only thing that I can think of is that the name you're asking for is
wrong (isn't the real device name), or that there's a bug in resolution
for NetBIOS names with - characters in them. What sort of device are we
talking about (it's not Windows Mobile, for example?)? Version of CE?
Networking components built in?

Your code works fine on my device.

Paul T.

I have this code:

try
{
IPAddress[] addresses =
Dns.GetHostEntry("david-1").AddressList;
foreach (IPAddress address in addresses)
{
if (address.AddressFamily ==
AddressFamily.InterNetwork)
{
m_strServeIP = address.ToString();
break;
}
}
}
catch (SocketException ex)
{
MessageBox.Show(ex.Message);
Close();
return;
}

A SocketException is thrown "No such host is known".

Yet, I know I have connectivity since I can browse the internet and I
have a valid ip address and it can be pinged from the david-1 computer.
My DHCP server is giving out dns and gateway information. Why does the
GetHostEntry fail?

 

[David]

You are correct. www.microsoft.conm resolved fine. Now I really need to know
how to resolve a computer name. I hope that someone can answer this.


"Paul G. Tobey [eMVP]" <p space tobey no spam AT no instrument no spam DOT
com> wrote in message news:[email protected]...

I'm no Vista expert. Try resolving www.microsoft.com. I'm pretty sure
that will work.

Paul T.

If I substitute 10.0.0.20 for david-1, everything works fine. That is,
the functionality of my app works to connect to the PC and retrieve data
and send data. So this tells me that I have connectivity to the network.
It is just that DNS seems not work work. Does Vista not use netbios
names? I am pretty sure that it does.

"Paul G. Tobey [eMVP]" <p space tobey no spam AT no instrument no spam
DOT com> wrote in message news:[email protected]...

The only thing that I can think of is that the name you're asking for is
wrong (isn't the real device name), or that there's a bug in resolution
for NetBIOS names with - characters in them. What sort of device are we
talking about (it's not Windows Mobile, for example?)? Version of CE?
Networking components built in?

Your code works fine on my device.

Paul T.

I have this code:

try
{
IPAddress[] addresses =
Dns.GetHostEntry("david-1").AddressList;
foreach (IPAddress address in addresses)
{
if (address.AddressFamily ==
AddressFamily.InterNetwork)
{
m_strServeIP = address.ToString();
break;
}
}
}
catch (SocketException ex)
{
MessageBox.Show(ex.Message);
Close();
return;
}

A SocketException is thrown "No such host is known".

Yet, I know I have connectivity since I can browse the internet and I
have a valid ip address and it can be pinged from the david-1 computer.
My DHCP server is giving out dns and gateway information. Why does the
GetHostEntry fail?

 

[Paul G. Tobey [eMVP]]

NetBIOS names are resolved via NetBIOS name registration. Internet names
are resolved via DNS. Dns.GetHostEntry does *NOT* imply that DNS is
*actually* being used, any more than the native WinSock call gethostbyname()
does. "Dns" was a poor choice of class names...

Paul T.

Ok, I can buy into that. However, I work from home and my network resolves
the name requests through my Windows Server 2008 system.

Just curious, in a network like your office network, where do the names
get resolved?

"Paul G. Tobey [eMVP]" <p space tobey no spam AT no instrument no spam DOT
com> wrote in message news:[email protected]...

I'm no Vista expert. Try resolving www.microsoft.com. I'm pretty sure
that will work.

Paul T.

If I substitute 10.0.0.20 for david-1, everything works fine. That is,
the functionality of my app works to connect to the PC and retrieve data
and send data. So this tells me that I have connectivity to the network.
It is just that DNS seems not work work. Does Vista not use netbios
names? I am pretty sure that it does.

"Paul G. Tobey [eMVP]" <p space tobey no spam AT no instrument no spam
DOT com> wrote in message The only thing that I can think of is that the name you're asking for
is wrong (isn't the real device name), or that there's a bug in
resolution for NetBIOS names with - characters in them. What sort of
device are we talking about (it's not Windows Mobile, for example?)?
Version of CE? Networking components built in?

Your code works fine on my device.

Paul T.

I have this code:

try
{
IPAddress[] addresses =
Dns.GetHostEntry("david-1").AddressList;
foreach (IPAddress address in addresses)
{
if (address.AddressFamily ==
AddressFamily.InterNetwork)
{
m_strServeIP = address.ToString();
break;
}
}
}
catch (SocketException ex)
{
MessageBox.Show(ex.Message);
Close();
return;
}

A SocketException is thrown "No such host is known".

Yet, I know I have connectivity since I can browse the internet and I
have a valid ip address and it can be pinged from the david-1
computer. My DHCP server is giving out dns and gateway information.
Why does the GetHostEntry fail?

 

[Chris Tacke, eMVP]

Is the machine you're trying to resolve in a domain? If so you might try
with a domain suffix (i.e. david1.mydomain.net) to see if the PDC (or
whatever internal DNS server you're using) will resolve it for you. I'm
pretty sure that Paul is correct that it's something to do with the NetBIOS
name not being DNS resolvable, though I'm not sure if it's VIsta related or
not (I try to avoid Vista). You might also try a local XP machine too to
see if there is a behavioral difference.

I'd also consider it worthwhile to do a test from desktop-to-desktop machine
to see if the same code resolves for them in the same network.

--

Chris Tacke, Embedded MVP
OpenNETCF Consulting
Giving back to the embedded community
http://community.OpenNETCF.com

You are correct. www.microsoft.conm resolved fine. Now I really need to
know how to resolve a computer name. I hope that someone can answer this.


"Paul G. Tobey [eMVP]" <p space tobey no spam AT no instrument no spam DOT
com> wrote in message news:[email protected]...

I'm no Vista expert. Try resolving www.microsoft.com. I'm pretty sure
that will work.

Paul T.

If I substitute 10.0.0.20 for david-1, everything works fine. That is,
the functionality of my app works to connect to the PC and retrieve data
and send data. So this tells me that I have connectivity to the network.
It is just that DNS seems not work work. Does Vista not use netbios
names? I am pretty sure that it does.

"Paul G. Tobey [eMVP]" <p space tobey no spam AT no instrument no spam
DOT com> wrote in message The only thing that I can think of is that the name you're asking for
is wrong (isn't the real device name), or that there's a bug in
resolution for NetBIOS names with - characters in them. What sort of
device are we talking about (it's not Windows Mobile, for example?)?
Version of CE? Networking components built in?

Your code works fine on my device.

Paul T.

I have this code:

try
{
IPAddress[] addresses =
Dns.GetHostEntry("david-1").AddressList;
foreach (IPAddress address in addresses)
{
if (address.AddressFamily ==
AddressFamily.InterNetwork)
{
m_strServeIP = address.ToString();
break;
}
}
}
catch (SocketException ex)
{
MessageBox.Show(ex.Message);
Close();
return;
}

A SocketException is thrown "No such host is known".

Yet, I know I have connectivity since I can browse the internet and I
have a valid ip address and it can be pinged from the david-1
computer. My DHCP server is giving out dns and gateway information.
Why does the GetHostEntry fail?

 

[Paul G. Tobey [eMVP]]

OK, you have a single PC at home? The Windows Server system? Or that
machine is remote? If you have two PC-type machines, open a MS-DOS window
on one of them and try to view the network information for the one whose
name you're currently trying to resolve, using the machine name. For
example,

net view \\david-1

If this works, that indicates to me that you have name resolution. That
would point to a possible problem with the resolution capabilities on the
device. If it does not work, that points to your name resolution system (PC
problem).

If the former is the case and the device is indicated as the problem source,
try renaming the machine whose name you are trying to resolve from "david-1"
to something without that nasty - character like "david1". Does that work?

Paul T.

You are correct. www.microsoft.conm resolved fine. Now I really need to
know how to resolve a computer name. I hope that someone can answer this.


"Paul G. Tobey [eMVP]" <p space tobey no spam AT no instrument no spam DOT
com> wrote in message news:[email protected]...

I'm no Vista expert. Try resolving www.microsoft.com. I'm pretty sure
that will work.

Paul T.

If I substitute 10.0.0.20 for david-1, everything works fine. That is,
the functionality of my app works to connect to the PC and retrieve data
and send data. So this tells me that I have connectivity to the network.
It is just that DNS seems not work work. Does Vista not use netbios
names? I am pretty sure that it does.

"Paul G. Tobey [eMVP]" <p space tobey no spam AT no instrument no spam
DOT com> wrote in message The only thing that I can think of is that the name you're asking for
is wrong (isn't the real device name), or that there's a bug in
resolution for NetBIOS names with - characters in them. What sort of
device are we talking about (it's not Windows Mobile, for example?)?
Version of CE? Networking components built in?

Your code works fine on my device.

Paul T.

I have this code:

try
{
IPAddress[] addresses =
Dns.GetHostEntry("david-1").AddressList;
foreach (IPAddress address in addresses)
{
if (address.AddressFamily ==
AddressFamily.InterNetwork)
{
m_strServeIP = address.ToString();
break;
}
}
}
catch (SocketException ex)
{
MessageBox.Show(ex.Message);
Close();
return;
}

A SocketException is thrown "No such host is known".

Yet, I know I have connectivity since I can browse the internet and I
have a valid ip address and it can be pinged from the david-1
computer. My DHCP server is giving out dns and gateway information.
Why does the GetHostEntry fail?

 

[David]

Yes, the same code works on my Vista laptop (david-2). I correctly get the
ip address of the david-1 computer.

Is the machine you're trying to resolve in a domain? If so you might try
with a domain suffix (i.e. david1.mydomain.net) to see if the PDC (or
whatever internal DNS server you're using) will resolve it for you. I'm
pretty sure that Paul is correct that it's something to do with the
NetBIOS name not being DNS resolvable, though I'm not sure if it's VIsta
related or not (I try to avoid Vista). You might also try a local XP
machine too to see if there is a behavioral difference.

I'd also consider it worthwhile to do a test from desktop-to-desktop
machine to see if the same code resolves for them in the same network.

--

Chris Tacke, Embedded MVP
OpenNETCF Consulting
Giving back to the embedded community
http://community.OpenNETCF.com

You are correct. www.microsoft.conm resolved fine. Now I really need to
know how to resolve a computer name. I hope that someone can answer this.


"Paul G. Tobey [eMVP]" <p space tobey no spam AT no instrument no spam
DOT com> wrote in message news:[email protected]...

I'm no Vista expert. Try resolving www.microsoft.com. I'm pretty sure
that will work.

Paul T.

If I substitute 10.0.0.20 for david-1, everything works fine. That is,
the functionality of my app works to connect to the PC and retrieve
data and send data. So this tells me that I have connectivity to the
network. It is just that DNS seems not work work. Does Vista not use
netbios names? I am pretty sure that it does.

"Paul G. Tobey [eMVP]" <p space tobey no spam AT no instrument no spam
DOT com> wrote in message The only thing that I can think of is that the name you're asking for
is wrong (isn't the real device name), or that there's a bug in
resolution for NetBIOS names with - characters in them. What sort of
device are we talking about (it's not Windows Mobile, for example?)?
Version of CE? Networking components built in?

Your code works fine on my device.

Paul T.

I have this code:

try
{
IPAddress[] addresses =
Dns.GetHostEntry("david-1").AddressList;
foreach (IPAddress address in addresses)
{
if (address.AddressFamily ==
AddressFamily.InterNetwork)
{
m_strServeIP = address.ToString();
break;
}
}
}
catch (SocketException ex)
{
MessageBox.Show(ex.Message);
Close();
return;
}

A SocketException is thrown "No such host is known".

Yet, I know I have connectivity since I can browse the internet and I
have a valid ip address and it can be pinged from the david-1
computer. My DHCP server is giving out dns and gateway information.
Why does the GetHostEntry fail?

 

[David]

I have many computers, one of which is the server.

I just tried new view \\david-1 on my david-2 vista laptop. It came back
with "There are no entries in the list."

The Dns.GetHostEntry("david-1") code works fine on the laptop though. It
returns the correct ip address of david-1.

"Paul G. Tobey [eMVP]" <p space tobey no spam AT no instrument no spam DOT
com> wrote in message news:[email protected]...

OK, you have a single PC at home? The Windows Server system? Or that
machine is remote? If you have two PC-type machines, open a MS-DOS window
on one of them and try to view the network information for the one whose
name you're currently trying to resolve, using the machine name. For
example,

net view \\david-1

If this works, that indicates to me that you have name resolution. That
would point to a possible problem with the resolution capabilities on the
device. If it does not work, that points to your name resolution system
(PC problem).

If the former is the case and the device is indicated as the problem
source, try renaming the machine whose name you are trying to resolve from
"david-1" to something without that nasty - character like "david1". Does
that work?

Paul T.

You are correct. www.microsoft.conm resolved fine. Now I really need to
know how to resolve a computer name. I hope that someone can answer this.


"Paul G. Tobey [eMVP]" <p space tobey no spam AT no instrument no spam
DOT com> wrote in message news:[email protected]...

I'm no Vista expert. Try resolving www.microsoft.com. I'm pretty sure
that will work.

Paul T.

If I substitute 10.0.0.20 for david-1, everything works fine. That is,
the functionality of my app works to connect to the PC and retrieve
data and send data. So this tells me that I have connectivity to the
network. It is just that DNS seems not work work. Does Vista not use
netbios names? I am pretty sure that it does.

"Paul G. Tobey [eMVP]" <p space tobey no spam AT no instrument no spam
DOT com> wrote in message The only thing that I can think of is that the name you're asking for
is wrong (isn't the real device name), or that there's a bug in
resolution for NetBIOS names with - characters in them. What sort of
device are we talking about (it's not Windows Mobile, for example?)?
Version of CE? Networking components built in?

Your code works fine on my device.

Paul T.

I have this code:

try
{
IPAddress[] addresses =
Dns.GetHostEntry("david-1").AddressList;
foreach (IPAddress address in addresses)
{
if (address.AddressFamily ==
AddressFamily.InterNetwork)
{
m_strServeIP = address.ToString();
break;
}
}
}
catch (SocketException ex)
{
MessageBox.Show(ex.Message);
Close();
return;
}

A SocketException is thrown "No such host is known".

Yet, I know I have connectivity since I can browse the internet and I
have a valid ip address and it can be pinged from the david-1
computer. My DHCP server is giving out dns and gateway information.
Why does the GetHostEntry fail?

 

[David]

The net view \\david-1 shows the no entries because I do not have any shares
on david-1.

net view \\mainserver (the server) comes back with results since it does
have shares.

I have many computers, one of which is the server.

I just tried new view \\david-1 on my david-2 vista laptop. It came back
with "There are no entries in the list."

The Dns.GetHostEntry("david-1") code works fine on the laptop though. It
returns the correct ip address of david-1.

"Paul G. Tobey [eMVP]" <p space tobey no spam AT no instrument no spam DOT
com> wrote in message news:[email protected]...

OK, you have a single PC at home? The Windows Server system? Or that
machine is remote? If you have two PC-type machines, open a MS-DOS
window on one of them and try to view the network information for the one
whose name you're currently trying to resolve, using the machine name.
For example,

net view \\david-1

If this works, that indicates to me that you have name resolution. That
would point to a possible problem with the resolution capabilities on the
device. If it does not work, that points to your name resolution system
(PC problem).

If the former is the case and the device is indicated as the problem
source, try renaming the machine whose name you are trying to resolve
from "david-1" to something without that nasty - character like "david1".
Does that work?

Paul T.

You are correct. www.microsoft.conm resolved fine. Now I really need to
know how to resolve a computer name. I hope that someone can answer
this.


"Paul G. Tobey [eMVP]" <p space tobey no spam AT no instrument no spam
DOT com> wrote in message I'm no Vista expert. Try resolving www.microsoft.com. I'm pretty sure
that will work.

Paul T.

If I substitute 10.0.0.20 for david-1, everything works fine. That is,
the functionality of my app works to connect to the PC and retrieve
data and send data. So this tells me that I have connectivity to the
network. It is just that DNS seems not work work. Does Vista not use
netbios names? I am pretty sure that it does.

"Paul G. Tobey [eMVP]" <p space tobey no spam AT no instrument no spam
DOT com> wrote in message
The only thing that I can think of is that the name you're asking for
is wrong (isn't the real device name), or that there's a bug in
resolution for NetBIOS names with - characters in them. What sort of
device are we talking about (it's not Windows Mobile, for example?)?
Version of CE? Networking components built in?

Your code works fine on my device.

Paul T.

I have this code:

try
{
IPAddress[] addresses =
Dns.GetHostEntry("david-1").AddressList;
foreach (IPAddress address in addresses)
{
if (address.AddressFamily ==
AddressFamily.InterNetwork)
{
m_strServeIP = address.ToString();
break;
}
}
}
catch (SocketException ex)
{
MessageBox.Show(ex.Message);
Close();
return;
}

A SocketException is thrown "No such host is known".

Yet, I know I have connectivity since I can browse the internet and
I have a valid ip address and it can be pinged from the david-1
computer. My DHCP server is giving out dns and gateway information.
Why does the GetHostEntry fail?