Network troubleshooting tutorial for beginners

sam3678

I think the following link will be useful for beginners in networking:
Internet troubleshooting in 4 steps , even though it is very simple , understanding this step by step procedure will be very useful,

sam

Xenz

Those tips are kind of off. For one, pinging doesn't always return a reply when everything is configured right either by ACL's or firewalls, or both.

Second, just having an IP doesn't mean much. What about the 169.254 APIPA addresses?

I think you're on the right track, just make sure you step back and see the big picture.

sam3678

Xenz wrote: »

Those tips are kind of off. For one, pinging doesn't always return a reply when everything is configured right either by ACL's or firewalls, or both.

Second, just having an IP doesn't mean much. What about the 169.254 APIPA addresses?

I think you're on the right track, just make sure you step back and see the big picture.

Xenz, these tips may not be the last thing we should we try, but for a beginner in networking we can assume that these will be helpful.

Xenz

Yes, but if you're beginning it's much better to get some more facts out. What happens if a beginner runs into a situation that I mentioned above? They get frustrated and change a bunch of things that don't need to be changed. You don't have to change your post, just saying you should add a few more details or note the situations where those tips may be false.

Just because they're beginners doesn't mean they can't learn!

sam3678

Xenz, U r rit, they may run in to those situations where some ACLs may be blocking traffic,Firewalls may be installed in the system,may be problem with modems,some software issues in the PC etc...
but that tutorial is about simple network problem that may happen in often in small networks and those steps are the first things we should try out... it is not about the big problems and I'm not against learning about those, instead if we learned about simple common problems it will be help full to learn about the other big issues step by step

KGhaleon

That's what I assumed when I saw "Cable Modem" in that diagram.
Xenz is being picky.

Pash

Xenz wrote: »

Those tips are kind of off. For one, pinging doesn't always return a reply when everything is configured right either by ACL's or firewalls, or both.

Enlighten us....You have said in your own reply that there are situations where ICMP reply packets wont return to your host, examples should be provided to the OP.

Ping should always be used in your arsenal of early network issue troubleshooting. Don't assume it doesn't work when it only takes a few seconds to try....but that should be obvious.

It should also be mentioned that tracert and pathping (sorry I don't know the linux commands for these, they are probably easy to find) also offer very handy network troubleshooting features.

Xenz wrote: »

Second, just having an IP doesn't mean much. What about the 169.254 APIPA addresses?

However, this is a valid point, it might be worth mentioning that windows hosts will not always get a valid private IP address, in which case APIPA comes into play.

Xenz wrote: »

I think you're on the right track, just make sure you step back and see the big picture.

He is on the right track, no doubt. I certainly see nothing in his blog post which isn't valid. My network troubleshooting is probably fairly bad in comparison to some of the guys on here, but my rule of thumb is always to follow the OSI model L1-L4, that way you cant look like a muppet by spending ages pinging a PC that doesn't have a network cable plugged in (which is basically what he is telling us).

Xenz

My point to the posts was there was an intended audience, either A) the audience here where this is very very basic and not complete information, or towards people who want to learn networking.

If more details should be added because what if a user pings his other computer and it doesn't work, at which point they change the IP or subnet mask. They then alter things that aren't really a problem and create a bigger mess.

I did mention situations in which a ping would fail.

I'm not bashing him, I'm saying he should add more details so that either audience has further understanding of these tools. I never said don't use ping, I simply said just because it fails doesn't mean it isn't working. Take it for what you will.

rsutton

A good start! I agree that ping/ipconfig should be in your first few steps. I would also add something about the 169 APIPA addresses. IE If you get a 169 address this means communication between the client and DHCP server (your router) is not working. Check cables or whatever you think the next step should be.

Also, the first thing I do when troubleshooting my home network is look at the lights on my cable modem. This saves me troubleshooting LAN issues if I see my DSL/WAN light not on.

Pash

Xenz wrote: »

My point to the posts was there was an intended audience, either A) the audience here where this is very very basic and not complete information, or towards people who want to learn networking.

If more details should be added because what if a user pings his other computer and it doesn't work, at which point they change the IP or subnet mask. They then alter things that aren't really a problem and create a bigger mess.

I did mention situations in which a ping would fail.

I'm not bashing him, I'm saying he should add more details so that either audience has further understanding of these tools. I never said don't use ping, I simply said just because it fails doesn't mean it isn't working. Take it for what you will.

Sorry im still missing where you said ping would fail, unless I cant see the post for some reason.

shadown7

Xenz wrote: »

...either by ACL's or firewalls, or both.

This is where I believe he is talking about pings failing. You can create ACL's and / or firewall rules that block ping.

Keith

Pash

shadown7 wrote: »

This is where I believe he is talking about pings failing. You can create ACL's and / or firewall rules that block ping.

Keith

For one, pinging doesn't always return a reply when everything is configured right either by ACL's or firewalls, or both.

Sorry I guess I miss-read the sentance.

In this case Id still say too much info at this stage isn't needed and not warranted in his beginners guide. A guide to cover potentially every firewall or router/L3 switch vendor would be a complete mess.

blackninja

Welcome to the forum

Great guide for the networking novice.

The only important thing (as rsutton stated) that is missing is to check the lights on your adsl/cable modem. In fact this should be the first thing you should check, as you may have just lost sync & a simple on/off usually works.