sqlserver ServerIP vs ServerName

[mikeb]

I've searched all over and have not found a reason - I'm really looking to
post this to MS to find the cause.

I have a MSDE database (or SQLserver for that matter) - a PC app connects to
it as does our PPC/scanners. The PC app always connects to the database,
where one or more PPCs get a "Specified SQL server not found" error when it
tries to connect. The config parms are correct. The only way around it is
to put the database server's IP address in place of the servername.

And whats stranger, even tho its on only certain device (strange enough
imo), something will cause a device to stop connecting with the message and
make us enter the ip address to get it to connect again.

What in the world is causing this? I've seen many many messages where the
developer is getting the 'specified sql server not found...' message, but
its always the same suggestions.

Why would one ppc require an ip and another work find with a server name???
Is this an OS issue? I have over 200 ppc's deployed with a small percentage
having this issue -

Does MS know of this issue, just not reporting it? Or do you have reference
to a KB article describing it?

Thanks!

Mike

 

[Arun]

Mike,

Pocket PC uses registry for DNS resolution machine name against IP
address But Desktop PCs use hosts file to resolve DNS.
If your SQL Server IP is DHCP configured,
PPC will face problem and DNS will not resolve properly.
A soft boot will always solve this problem.

But it is advicable to use IP instead of machine name so that PPC will
not look in registry for IP address.

Hope this helps,
Cheers,
Arun.
www.innasite.com

 

[mikeb]

Thanks Arun
Our host sql servers have static IPs. I'm not sure if this answers your
saying, 'if your sql server ip is dhcp configured' though.

I guess I'm looking for an explanation as to why it has problems on some
devices but not others. Can you explain further? What is stored in the
registry, hostname to IP address map I assume? On the PC app, it seems we
rely on a dns server to handle the pcname requests, since we're not touching
the hosts file. Wouldnt' the ppc do the same?

Sorry, I just want to really understand how this works, so I can better
support it when the issue arises again.

Strongly suggesting that they use IP address instead of computer names does
sound logical - but I would just really like to understand more of the "why"
too.

Thanks again.

 

[Arun]

What is stored in the

registry, hostname to IP address map I assume? On the PC app, it seems we
rely on a dns server to handle the pcname requests, since we're not touching
the hosts file. Wouldnt' the ppc do the same?

In PPC IP Addresses are stored as strings in the registry
"HKLM\\Comm\\Tcpip\\Hosts\\"
Something like this 192 168 2.3 to C0 A8 02 03

PPC lacks access to DNS server. So to resolve the machine name against
IP it looks for an entry in registry. Sometimes it fails to resolve.

How is your PPCs connected to your network?

Cheers,
Arun.
www.innasite.com

 

[mikeb]

Thanks for the clarification. Thats good information to know.

My first question to you is, where do you find this stuff out? I'd like to
know more about the internals of PPC so I can better develop for them.

To answer your question, our PPCs are wired to the network via a ethernet
enabled dock which is connected to a network hub or switch. Most use DHCP
to attain their IP addresses; others, if the network doesn't have dhcp, will
have a static IP assigned to them.

Since you say PPCs don't use DNS how do machine names ever get resolved?? I
never put anything into the hosts file (er, registry) and yet when I type
MYPCNAME\MyMSDBInstance - most of my PPC scanners know that MYPCNAME is
assigned to xxx.xxx.xx.xxx on the network. There must be some type of dns
going on? I'm definitely not telling the PPC that MYPCNAME =
xxx.xxx.xx.xxx.

?

Thanks!

Mike

 

[Arun]

Mike,

I feel MSDN is the best book,
Check this link to know more about the Name Resolution

http://msdn.microsoft.com/library/d...st_Name_Resolution_Using_Registry_Entries.asp

Hope this helps,
Cheers,
Arun.
www.innasite.com

 

[Arun]

Mike, Check this link too,

http://msdn.microsoft.com/library/d...st_Name_Resolution_Using_Registry_Entries.asp

If there is an entry for your DNS Server Name in registry
("HKLM\\Comm\\interface\\TCPIP\\Parms\\DNSDomain"), I guess your PPCs
will work without any problems.

Good luck.
Cheers,
Arun.
www.innasite.com

 

[mikeb]

Thanks for the links. But I guess I'm still not sure why a pcname would
ever work if I never add it to the registry.

I have on PPC where it connects fine, then I change to IP and it works fine,
but when I go back to the PCname, it fails - until at some point, it
connects. I'd sure like to figure this out so I don't go completely insane
taking all these support calls. Something has to be happening in the
background to set off either a write to this registry key, or that finally
resolves the machine name.

Am I the only one that sees this type of behavior?