Last Updated 10/28/2006


Go to the Frequently Asked Questions (FAQ)

What's New

  • If you are an Internet Explorer User, I highly recommend that you download IE7.  I've used it for about a week now, and I really like the new fonts and FireFox-like tabs. (10/28/2006).
  • I see this page is getting more traffic lately. So, I checked and updated old links and notes (08/12/2006).
  • I added a Helpful Troubleshooting Utilities Section Below.  (01/30/2003)
  • Please note that latest DUN version is Windows 95/98 DUN 1.4.   Thanks to Emmanuel Piring for letting me know there was a new version available.   (11/11/2001)

Helpful Troubleshooting Utilities/Information


This is an attempt to document some common problems that you might have with your dial-up TCP/IP connection. Originally, this page was made to address using Trumpet Winsock and SLIP emulation software. The focus of this guide will now be on troubleshooting Dial-Up TCP/IP networking connections in general, which should apply to a wide range of dial-up TCP stacks, Windows 95 DUN (Dial Up Networking) and Windows NT RAS. If you would like to advertise on this page (Dreaming in color here), please contact me at the e-mail address below. 

If you have suggestions, find errors or have a solution you would like to add to this document, please e-mail it to me. I will include your e-mail address or name if you desire with the solution. Disclaimer.

Sorry, but I do not have time to answer your personal questions.  

Copyright Notice: Copyright (c) Lynn D. Larrow 1995-2006.
You must have permission of the author, Lynn Larrow, to use any information contained in this or any other document contained on my site. Maintained by Lynn Larrow.

The URL for this page is Since 4/1/95, this page has been accessed:  

Troubleshooting Menu

Dial-Up and Home Networking Frequently Asked Questions
  • 1.01 Help! My Dial-Up PPP connection doesn't work! (08/12/2006)
  • 1.02 When I try to connect to a site, e.g.,, I keep getting DNS or not found errors.
  • 1.03 I can login, but I can't get my login script to work.
  • 1.04 I connect to my Internet Service Provider (ISP), but I have problems running, e.g., Netscape, mail.
  • 1.05 I have problems connecting to my server at 33,600 baud.
  • 1.06 How do I start Windows 95/NT/XP from the command line or in a script? (08/12/2006)
  • 1.07a How do I determine my DNS servers for my ISP?
  • 1.07b Is there a Web based tool for doing Pings, DNS lookups and traceroutes?  (12/26/2001)
  • 1.07c How can I tell what my IP Address is?  (01/30/2003)
  • 1.09 What are the optimal values for MTU and MSS?
  • 1.10a Where can I find a good FAQ on 28800+ Modems? (3/17/2001)
  • 1.10b Where can I find a good FAQ for configuring DSL and Cable Modems? (3/17/2001)
  • 1.10c Where can I find a good FAQ for finding ISPs and testing DSL and Cable Modems? (12/26/2001)
  • 1.11 Where can I find more information on communications and networking plus FREE Utilities? (3/17/2001)
  • 1.12a What is a firewall? Where is the Internet Firewalls FAQ? (3/17/2001)
  • 1.12b How can I tell if my PC is secure on the Internet? (3/17/2001)
  • 1.12c Is there a great free firewall out there? (ZoneAlarm - I use and recommend this one) (12/26/2001)
  • 1.12d Where can I learn more about Home Network Security? (CERT FAQ)  (02/15/2002)
  • 1.14 What is SLiRP?
  • 1.15 I'm using Windows 95/98/NT/2000. Are there any good FAQs for Windoze?
  • 1.16 What's the difference between SLIP, PPP, and shell and which one is best for me?
  • 1.17 What is the hosts file used for and where does it go?
  • 1.18 What is a good source for questions about the Internet, etc.?
  • 1.19 What and where is the most recent version of Windows 95/98 DUN?
  • 1.20 Why can't I change my password when it expires with Windows 95 using a Windows NT RAS server?
  • 1.21 How do I Share a DSL or Cable Modem at Home?
  • Trumpet Winsock Specific Questions (I have not  looked at this Trumpet stuff since 1996 maybe?) 12/26/2001


    [Troubleshooting Menu]-[Home Page]

    1.01 Help my PPP/SLIP connection doesn't work.
    First thing you need to do is to check to make sure that you have installed Dial-Up TCP connection properly.  Make sure you follow all of the instructions provided to you from your Internet Service Provider (ISP):

    Also, use ipconfig /all from the command line to check your XP/2000 PPP connection. To get to the command line, select Start->Run->cmd <return>. Note: use winipcfg for Windows 95/98.

    Here's an example of what Your PPP connection settings should look like if you are connecting correctly to your ISP.  Please note that nearly all IP PPP configurations are dynamic IP Address, i.e, you don't have to enter any of this information.  If you have a static connection, then you would have to enter your IP and DNS addresses.

    PPP adapter SBC Global:
            Connection-specific DNS Suffix  . :
            Description . . . . . . . . . . . : WAN (PPP/SLIP) Interface
            Physical Address. . . . . . . . . : 00-53-45-00-00-00
            Dhcp Enabled. . . . . . . . . . . : No
            IP Address. . . . . . . . . . . . :
            Subnet Mask . . . . . . . . . . . :
            Default Gateway . . . . . . . . . :
            DNS Servers . . . . . . . . . . . :
            NetBIOS over Tcpip. . . . . . . . : Disabled

    Windows XP: How To Configure and Use Dial-Up Connections in Windows XP.

    Windows 95/98: How to Connect to the Internet in Windows 95/98.

    Windows NT 4.0/2000: Troubleshooting Internet Service Provider Login Problems.

    Trumpet Winsock: If you are still using Slirp and Trumpet Winsock, please see my SLiRP installation instructions, e.g., .slirprc file. Make sure you have downloaded the correct version of SLiRP/TIA for your host computer. If you are PPP user, here is my trumpwsk.ini.

    1.02 When I try to connect to a site, e.g.,, I keep getting DNS errors or not found.
    Domain Name System or DNS is the way TCP/IP resolves computer names to IP addresses much like a phone book lets you look up telephone numbers by name. If your DNS server is not correctly specified, you will be unable resolve or look-up computers by name.

    Assuming the IP address of is If you cannot access, but you can access then you most likely have a DNS problem.  The White House does change this IP address from time to time so double check the address with a lookup from Network Tools for example.

    Most ISP's now support dynamically assigning DNS addresses when you login into their PPP server. In this case, make sure that your DNS entries are left blank . Otherwise, check with your ISP to verify what your DNS server addresses should set to.

    Windows 95 users on a LAN using a local static DNS address may experience this problem documented by Microsoft: DNS Settings in Dial-Up Networking Connectoid Are Not Used. Microsoft's resolution to this problem is to set your DNS for your network card to your ISP's DNS server and to create a hosts file to resolve local names. This problem has been corrected with version 1.3 of DUN.

    1.03 I can login, but I can't get my login script to work.
    Windows XP: See Microsoft Windows XP - Rasdial.

    See also: #1.06 below for other Windows versions.

    Trumpet Winsock: Use my Pacbell PPP login.cmd or SLiRP login.cmd for a comparison with your script. If all the settings match, you will probably need to check your modem documentation or this URL for your modem setup string. Also, I have noticed that if you try to put "exec slirp" in a $variable name, e.g., $slipcmd that Trumpet will think you are trying to start (execute) a file on your local PC.

    1.04 I connect to my Internet Service Provider (ISP), but I have problems running, e.g., Netscape, mail.
    When you configure winsock applications like Internet Explorer, Microsoft Outlook, Netscape or Eudora mail you need to make sure that you have the right server names specified. Below are server types that you will need to get from your ISP. I have used Best as an example. You will need to get the correct names from your ISP. If you have trouble contacting your ISP, or want to get information about a domain's DNS MX entries (e-mail), check with the Network Tools or DNS Stuff: DNS and other IP Tools to look the DNS MailB Querytype. If you are unsure or cannot find   your ISP POP or SMTP server name, try looking up using host name for common server name as in the examples below.
    POP mail server
    SMTP mail server
    NNTP or News server

    1.05 I have problems connecting to my server at 56K line bps.
    Make sure that you have selected the right modem driver (in the modem control panel entry for Windows 95 and Windows NT) and that you have hardware handshaking flow control set on. 

    See also: Navas 28800-56K Modem FAQ.

    See my Communications FAQs and Links for more information.

    1.06 How do I start Windows 95 or Windows NT DUN from the command line or automatically?

    Windows XP: To Dial: rasdial connectionname [username [password | *]] To Disconnect: rasdial [connectionname] /disconnect 

    rasdial "SBC Global" username password
    rasdial "SBC Global" /disconnect

    Reference: Microsoft Windows XP - Rasdial

    Windows 95: rundll rnaui.dll,RnaDial <connectoid> where connectoid is Microsoft jargon for the name of your dial-up networking target that you have already created, e.g., msn, aol, ... Please note a "hands free" option is now available with DUN 1.3.

    rundll rnaui.dll,RnaDial PacBell


    How to Start Dial-Up Networking Connection Using Command Line.

    How to Make a Hands-Free Dial-Up Connection in Windows 95

    Windows NT/2000: rasphone -d <entry> where entry is the name of the dial-up entry in your phone book. For example: I put the following entries into a batch file in my startup group to dial PacBell (my ISP) and then launch using Internet Explorer 4.0.

    rasphone -d PacBell

    Reference: RASPHONE and RASDIAL Tips and Differences for NT/2000.

    1.07 How do I determine my DNS servers for my ISP?
    Many ISPs support server assigned IP, Gateway and DNS addresses, which means you usually don't have to worry about what your addresses are. You can check what your IP settings by executing from the DOS prompt:

    Windows 95/98: winipcfg

    Windows NT/2000: ipconfig /all

    However, if you suspect you need to manually specify these addresses, consult your documentation or call your ISP technical support person for these IP addresses. If you have trouble getting a hold of support, you can see what your ISP DNS server(s) are by using the whois [] command in UNIX,  Network Tools or with a winsock whois client like the one in Sam Spade. If you have several choices for DSN, see which DNS server has the best response time by using ping and traceroute. Remember to check with your ISP to determine which DNS server you should be using from your location.


    {netcom10:1} whois
       Domain Name: BEST.COM
       Record last updated on 10-Jan-95.
       Domain servers in listed order:

    The DNS entries are also on the UNIX host computer in the file /etc/resolv.conf.


    {netcom10:2} more /etc/resolv.conf

    Your gateway could be determined by using the netstat -r command in UNIX or by using a traceroute program.

    {netcom19:10} netstat -r
    Routing tables
    Destination          Gateway              Flags    Refcnt Use        Interface
    localhost            localhost            UH       301    5727174    lo0
    default           UG       275    27592733   le0
    {netcom19:11} traceroute
    traceroute to (, 30 hops max, 40 byte packets
     1 (  3 ms  4 ms  4 ms
     2 (  4 ms  5 ms  8 ms
     6 (  11 ms  13 ms  10 ms

    1.15 I'm using Windows 95/98/NT/2000/XP. Are there any good FAQs for Windows and Internet connectivity?
    Microsoft Support Knowledge Base for all Windoze Versions
    Windows NT/2000/XP Frequently Asked Questions
    Win95 FAQ Part 8: The Internet/other dial-up questions

    1.17 What is the hosts file used for and where does it go?
    The host file can be used by the TCP stack to lookup or resolve host names on a LAN or on the Internet. In most cases, the DNS server is all you will need to worry about when you setup dial-up connection. However, there are times when a hosts file is needed: you don't have a local DNS server on your LAN, you want to simplify your winsock client setups perhaps for multiple ISPs, or maybe you use Windows 95 on a LAN and want to dial-up the Internet at the same time.

    One of the best features of the hosts file is that it can be changed on the fly. If you have several accounts that you log into, you could create hosts files for each ISP and then copy the desired hosts file before you dialed the target ISP. Notice that both files use an alias in the third column. These alias names are what you need to put into your browser, e-mail client, newsreader, etc.

    Caution: These settings override DNS and are static. If your ISP changes IP addresses on you, you will need to update these files.

    See Also: Host Name Resolution for more details from Microsoft.


    Hosts file for ISP1          localhost                  popmail       smtpmail           news

    Hosts file for ISP2          localhost        popmail       smtpmail           news

    The hosts file should reside in the following directories:

    Trumpet: c:\trumpet (or the directory you start trumpet in)
    Windows 3.x: c:\windows (or where your TCP stack is located)
    Windows 95: c:\windows
    Windows XP: c:\windows\system32\drivers\etc
    Windows NT/2000: c:\[systemroot]\system32\drivers\etc
    UNIX: /etc
    Netware IP: c:\nwclient\tcp (assuming your netware client is in nwclient)

    1.20 Why can't I change my password when it expires with Windows 95 using a Windows NT RAS server?
    Prior to Windows 95 DUN version 1.2, which was released this summer 1997, when you tired to log on to an NT RAS server and your password expired or the system otherwise forced you to change your password, you received a message to contact your system administrator. Since I have administered RAS servers, I was more than just a little ticked with Bill Gates over this bug. Well give Microsoft enough time (about 2 years) and they might even fix a silly bug like this.

    Ok I'll shut up.

    This problem is fixed if you update to Windows 95/98 DUN 1.4.

    1.21 How do I Share a DSL/Cable Modem at Home?
    Do your home work and make sure pick the solution (wireless or hard wired) that best meets your needs.  If you can afford it, I'd just go with wireless it's a lot more flexible and costs are fairly reasonable these days.

    Some Good Resources are:

    Home and Small Office Networking with Windows XP
    Howstuffworks "How Home Networking Works"
    How to troubleshoot home networking in Windows XP
    Sharing Cable Modem or DSL on multiple computers



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