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All about ping

Ping is a useful network diagnostic, but it can have its own issues - timeouts, duplicate packets, intermittent issues and more.

Title Last Comment
The Seven Layer inedible OSI cake  
- The other day I had to explain the OSI model to a customer. I'm not usually this cruel, but (as they say) he asked for it. -

Why use private network addresses  
- I still see systems where people have used public ip addresses for private networks. -

All about ping   2013/09/10 TonyLawrence
- Ping is a useful network diagnostic, but it can have its own issues - timeouts, duplicate packets, intermittent issues and more. -

Length of a domain name  
- What IS the longest possible domain name and why isn't it in the book of Guinness World Records? While we're at it, what is a domain name anyway? -

Mysterious Duplicate IP problem solved   2011/11/14 NickBarron
- I only needed to be run over by four or five cluetrains before realizing what was causing this 'IP address conflict' message on a Windows 2003 server. Follow along and see when you solve it. -

Internet phone service - without the service   2011/07/16 BigDumbDinosaur
- My wife is one who, once on the telephone, can't seem to know when to stop ta lking. Accordingly, our residential phone service bill tends to bear a vague resemblance to the national debt. She can't seem to bring herself to change her phone habits, so I finally caved in against my better judgment and gave her the go-ahead to switch our residential service to voice-over-IP (VoIP). After doing a bit of research, a company called TeleBlend was selected to provision the service. -

Mysterious Duplicate IP addresses   2011/04/20 TonyLawrence
- Proxyarp on smart switch causes sudden appearance of duplicate ip addresses: All machines on our 192.168.206.x subnet (mostly Mac's, with Windows servers) got the IP conflict message when they started up in the morning. We do have a linux dhcp server running on that subnet, but it only hands out 2 IP addresses for barcode guns, and those are given the IP based on their MAC address, so each barcode gun always gets the same IP and can move to other buildings without reconfiguring them, as they run in dhcp mode. -

Paradigm ImagePRO Ci40m HD TCP/IP setup   2010/04/16 TonyLawrence
- Okey-dokey. I double checked all the bad cable, bad port, ip conflict stuff. Nothing wrong there. -

Lan sniffing with a DualComm port mirroring switch and Windump   2010/01/23 TonyLawrence
- Using Dualcomm Port Mirroring switch and Windump to trace network problems and detect virus activity. -

Basic (very basic) TCP/IP  
- I recently had to explain TCP/IP to a non-technical person. What follows is basically what I came up with, though it doesn't have any of the hand waving, pointing or any of the other dramatic gestures and facial expressions I used to fill in the gaps. -

Port Forwarding Verizon?   2011/03/01 TonyLawrence
- Actiontec router not port forwarding - mistook meaninf of 'Source Ports' setting. -

Who said that?  
- This comes up fairly frequently. It also happens sometimes with remote TCP printers: if you haven't given them a gateway address, they can't communicate back to you. Packets need routes. -

Maximun number of socket connections  
- 100 connections hangs server.. configuration? Possible tuning limits on SCO Unix that might cause this. -

Understanding SOA records  
- DNS and SOA records: An important part of keeping DNS working well is properly setting up the SOA records. -

mtu: Tech Words the Day  
- Maximum Transmission Unit. Every time you send mail, or transfer a file on your local network, or indeed do anything at all that involves communicating with another machine, data is broken up into packets of a specific size. -

sack: Tech Words the Day  
- Selective Acknowledgements RFC-2018 are turned off or on in Linux by setting net.ipv4.tcp_sack (in /etc/sysctl.conf ) to 0 or 1. The purpose of this feature is to cut down on retransmisson of packets on bad networks. -

- A Bogon address is an ip address that shouldn't be in a routing table and therefore shouldn't be used for hosts or devices. These are not the just the reserved private addresses we use for internal networks. Bogon addresses are often used as the source addresses of DDoS packets. -

- In networking, a packet is the collection of information that carries your data to its destination. If you are, for example, sending a large email to a friend, it does not travel in a contiguous flow of bytes. Instead, it is broken up into chunks -

(SCO Unix)I see in netstat that processes get stuck in TIME_WAIT  
- (SCO Unix) For some reason, OpenServer sets TIME_WAIT to 30 minutes even while stating that the recommended setting is 4 minutes! -

LOD Communications, Inc.
telnet environment variables -->Re how to set env var bytelnet port no  
- telnet environment variables -->Re: how to set env var bytelnet port no -

kernel relink ip address change -->Re Why does thenetwork manager relink for IP changes  
- kernel relink ip address change -->Re: Why does the network manager relink for IP changes -