Many small business owners, like yourself, or a member of your staff double as the "IT Guy". Nothing wrong with this, but it does take time away from your business. Learning how computers work, operating systems, applications and connecting everything together is no small task.
Let's discuss a few common network troubleshooting steps to speed up the learning curve and maybe save you a call to your IT support company or Internet Service Provider (ISP).
First, we'll do a brief explanation of how a PC gets from point A to point B.
Your computer is connected to a network either via an Ethernet cable or wireless connection. Most small businesses or home users have a wireless router/gateway they purchased from one of the "Marts" or Tech Stores. These wireless routers are preconfigured, ready for you to connect the WAN (Wide Area Network) port to your Internet Service Provider (ISP) DSL/Cable Modem and for your PC(s) to connect to the LAN (Local Area Network) port(s).
After you connect your PC to the router/gateway, it grabs or pulls an IP Address via DHCP (Dynamic Host Configuration Protocol). Think of an IP Address like phone number, it is a unique number that your computer can be reached at.
When you ask your computer access a website, it does it much like you would make a phone call when you don't know the number. You pull out the phone book, scroll through the listings until you find the number, then dial. PC's use DNS, or Domain Name System, to find the number that correlates to the name you asked it for. (i.e. www.google.com). Your computer knows what DNS servers to ask because they were provided by DHCP, described above. Your internet provider has DNS servers for your PC to make these name lookup request.
Now that your PC knows what number to call, it send this request out to the information highway by asking that router/gateway to forward the request to your Internet Provider or ISP. Your ISP forwards it to the website and the website sends back the information that displays on your screen.
We have a basic knowledge of IP Addresses, DNS and that we get this information through DHCP, let's discuss a few troubleshooting steps.
Go to Start, Run and Type cmd, hit enter. A small black box will come up. In the box,
Type ipconfig, enter (Your IP Address will display along with Subnet Mask and Default Gateway, which is the router/gateway your purchased)
Connection-specific DNS Suffix . : nsn.local
IPv4 Address. . . . . . . . . . . : 192.168.100.100
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 192.168.100.1
Type ipconfig/all, enter (/all shows additional information such as your DHCP and DNS servers)
Connection-specific DNS Suffix . : nsn.local
Description . . . . . . . . . . . : Dell Wireless 1395 WLAN Mini-Card
Physical Address. . . . . . . . . : 00-22-69-3F-28-4A
DHCP Enabled. . . . . . . . . . . : Yes
Autoconfiguration Enabled . . . . : Yes
IPv4 Address. . . . . . . . . . . : 192.168.100.100(Preferred)
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Lease Obtained. . . . . . . . . . : Friday, November 20, 2009 8:02:22 PM
Lease Expires . . . . . . . . . . : Monday, November 23, 2009 8:02:36 PM
Default Gateway . . . . . . . . . : 192.168.100.1
DHCP Server . . . . . . . . . . . : 192.168.100.1
DNS Servers . . . . . . . . . . . : 208.67.222.222
208.67.220.220
NetBIOS over Tcpip. . . . . . . . : Enabled
Type ping Default Gateway (Ping verifies that you can get to another device and get a valid response, in this case, verifies your local network is working)
C:\>ping 192.168.100.1
Pinging 192.168.100.1 with 32 bytes of data:
Reply from 192.168.100.1: bytes=32 time=1ms TTL=255
Reply from 192.168.100.1: bytes=32 time=1ms TTL=255
Reply from 192.168.100.1: bytes=32 time=1ms TTL=255
Reply from 192.168.100.1: bytes=32 time=1ms TTL=255
Ping statistics for 192.168.100.1:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 1ms, Maximum = 1ms, Average = 1ms
Next, Type nslookup website, you want to access. Nslookup is similar to you looking up a phone number in the phone book. You should see at least one number returned under the non-authoritative answer: section.
C:\>nslookup www.google.com
Server: resolver1.opendns.com
Address: 208.67.222.222
Non-authoritative answer:
Name: www.l.google.com
Addresses: 209.85.225.105
209.85.225.147
209.85.225.103
209.85.225.104
209.85.225.99
209.85.225.106
Aliases: www.google.com
Next, ping the website. Keep in mind that not all websites allow ping so it isn't guaranteed to get a response. If you get a response, you're ISP is working fine.
C:\>ping www.google.com
Pinging www.l.google.com [209.85.225.103] with 32 bytes of data:
Reply from 209.85.225.103: bytes=32 time=42ms TTL=54
Reply from 209.85.225.103: bytes=32 time=41ms TTL=54
Reply from 209.85.225.103: bytes=32 time=41ms TTL=54
Reply from 209.85.225.103: bytes=32 time=42ms TTL=54
Ping statistics for 209.85.225.103:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 41ms, Maximum = 42ms, Average = 41ms
Question and Answer
Q. What do I do if I can't ping my default gateway?
A. Verify that your wireless connectivity is working or that your ethernet cable is connected from your PC to the gateway. There should be a link light on both the PC card, or NIC, and the gateway that verifies a connection is made.
Q. What do I do if there isn't a response to my nslookup request.
A. Assuming you can ping your default gateway, try to ping the DNS Address that shows after an ipconfig/all. If you can't, verify your connection from your router/gateway's WAN port to your cable/dsl modem. If a link light shows on both ends, you can log into your gateway and verify that the WAN port has an IP Address assigned from your ISP. If it doesn't, reset your gateway and call your Internet Provider.
Q. What do I do if I can ping www.google.com but can't get to it in a web browser.
A. If no web pages display, but you can ping them, this indicates a problem with your PC. Try rebooting first, then call your trusted PC Repairman.
NonStop Networks, LLC
Cisco Unified Communications Solutions
http://www.nonstopnetworks.net | http://forum.nonstopnetworks.net
Focused on solving problems for small and medium sized businesses who are frustrated that their communication systems are letting them down, worried about security and concerned with rising technology cost. Helping businesses communicate in real-time with customers and staff - anytime, anywhere.
There is no warranty in the information listed. It is always recommended that your seek the advice of a trusted professional.