October 27, 2008 at 4:19 pm
I have an SQL server on a laptop PC.
When working as a server, it is connected to my LAN. If the IP address is static, i can succesfully connect with any program, with a connection string of the kind:
Data Source=PRESARIOLT\SQLEXPRESS;Initial Catalog=Quaderno;Persist Security Info=True;User Id=User;Password=psw
Of course, this one also works:
Data Source=10.10.1.10\SQLEXPRESS;Initial Catalog=Quaderno;Persist Security Info=True;User Id=User;Password=psw
Today, I had to add a wireless access port, enabled as a DHCP server. In my LAN there is no DHCP server, any PC is connected to a static IP: the laptop can accept a dynamic IP, but i also assigned a static address in the "alternate configuration" in the TCP/IP settings. Please take note the a dynamic IP is assigned to bot connections, the ethernet and the wireless.
When the IP is dynamically assigned, i can not connect any more using the server name, that is, Data Source=PRESARIOLT\SQLEXPRESS does not work any more. What is working is Data Source=10.10.1.10\SQLEXPRESS.
It should work, if the IP were the same all the time, but, as it is dynamically assigned, it happens it can be different every time. I know it could even change when the leasing time expires (i do not know that much about networking: so, please forgive if i write silly things).
My LAN is a very simple one, there is no domain, just a workgroup. The router is furnished by the internet provider. It is connected to the ADSL, i do not know if it has a static or dynamic IP, and this should not matter. I have no control on the device: i just know its IP address, 10.10.1.1, i can not see it in the web browser (firefox says: "Though the site seems valid, the browser was unable to establish a connection .... Is your computer or network protected by a firewall or proxy?"). I believe i can not change any setting in it, and probably I should not.
Inside the LAN there is no DNS server: i was told to use two addresses that i believe are public DNS server: 212.17.192.49 and 212.17.192.209 (by the way: i can not understand hot the PCs can refer each other by name, but, as i wrote above, i am not a networking guru by no means).
Well ... what can i do? I anything can be done, of course.
Thank you in advance.
Aldo Marchioni.
October 27, 2008 at 4:27 pm
the public DNS servers will have no knowledge of your internal network naming
from a command prompt type the following and post the complete results
IPCONFIG/ALL
also what make\model is your router?
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"Ya can't make an omelette without breaking just a few eggs" 😉
October 27, 2008 at 6:54 pm
Thanks Perry.
I know the public DNS server has no knowledge of my LAN, actually, i wrote it, and i removed the note as i re-read, because my post was very long, and i believed it was so obvious that writing it could make me seem kinda a silly guy 😀
The IPCONFIG/ALL output is as follows (sorry, the OS language is italian, if you need any translation, please let me know):
Configurazione IP di Windows
Nome host . . . . . . . . . . . . . . : PresarioLT
Suffisso DNS primario . . . . . . . :
Tipo nodo . . . . . . . . . : Sconosciuto
Routing IP abilitato. . . . . . . . . : No
Proxy WINS abilitato . . . . . . . . : No
Scheda Ethernet Connessione alla rete locale (LAN):
Suffisso DNS specifico per connessione:
Descrizione . . . . . . . . . . . . . : NVIDIA nForce Networking Controller
Indirizzo fisico. . . . . . . . . . . : 00-16-36-9A-08-29
DHCP abilitato. . . . . . . . . . . . : Sì
Configurazione automatica abilitata : Sì
Indirizzo IP. . . . . . . . . . . . . : 10.10.1.100
Subnet mask . . . . . . . . . . . . . : 255.255.255.0
Gateway predefinito . . . . . . . . . : 10.10.1.1
Server DHCP . . . . . . . . . . . . . : 10.10.1.254
Server DNS . . . . . . . . . . . . . : 212.17.192.49
Lease ottenuto. . . . . . . . . . . . : martedì 28 ottobre 2008 1.30.05
Scadenza lease . . . . . . . . . . . : martedì 4 novembre 2008 1.30.05
Scheda Ethernet Connessione rete senza fili 2:
Suffisso DNS specifico per connessione:
Descrizione . . . . . . . . . . . . . : WLAN Broadcom 802.11b/g
Indirizzo fisico. . . . . . . . . . . : 00-14-A5-F9-9E-C7
DHCP abilitato. . . . . . . . . . . . : Sì
Configurazione automatica abilitata : Sì
Indirizzo IP. . . . . . . . . . . . . : 10.10.1.101
Subnet mask . . . . . . . . . . . . . : 255.255.255.0
Gateway predefinito . . . . . . . . . : 10.10.1.1
Server DHCP . . . . . . . . . . . . . : 10.10.1.254
Server DNS . . . . . . . . . . . . . : 212.17.192.49
Lease ottenuto. . . . . . . . . . . . : martedì 28 ottobre 2008 1.30.10
Scadenza lease . . . . . . . . . . . : martedì 4 novembre 2008 1.30.10
The wireless router is a digicom wavegate 54cx (a cheap model, indeed). The LAN router, i do not know. The IP provider installed it several years ago, it is located to a weird accessible spot, and the only thing i can read over it is "CELL".
So far, i have found that i can not ping my server by name. Just by IP. And, if i disable the DHCP service, and assigne a static IP, i can ping by name. So, this seems to be a networking problem, rather than an SQL connection problem.
I still can not understand how names are resolved, having no DNS nor WINS server ... i am puzzled. I see my understanding of networking is not excellent ... to say the least.
October 28, 2008 at 4:51 am
i would disable DHCP and assign each machine a static IP. check the hosts file on each pc to see if there are any entries in there. Its located in
C:\windows\system32\drivers\etc
or
C:\winnt\system32\drivers\etc
set the static IP's for each pc and add an entry into the hosts file for each then distribute the file to each pc that connects on the network
Ciao
perry
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"Ya can't make an omelette without breaking just a few eggs" 😉
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