IFSM 300 Networking. Bold edit this file in Word. Name:____________________________ Start the Command Prompt (CMD) (in Menus, Windows System) [or Mac Terminal]. Use the 'ipconfig' command (ifconfig on Mac) probably the part about "Wireless LAN adapter Wi-Fi:" [en0 on Mac] What's your computer's IP address? ___________ What is the Default Gateway (local router) IP address: ______________ [route on Mac)] 'ping' sends an ICMP Echo Request to, and gets ICMP Echo Response from, a computer/host. ping is the simplest communication. No data is exchanged. ping is the basic networking troubleshooting tool. You can use it to track down a problem by starting at the computer and moving progressively outward. Note: WiFi is too variable to get consistent ping times. ping -? to see the list of possible switches/options for ping 1. First question you need to know: Is TCP/IP networking working on the computer? In Command Prompt: ping localhost 'localhost' is always a synonym for self. In the unlikely event that TCP/IP is not installed or running, ping will indicate. Where is the ping reply coming from:________________ (this is a special IP address called the "loopback" device or address that is always associated with the local host.) IPv4 it is 127.0.0.1 IPv6 it is ::1 ping -4 localhost to force IPv4 Where is the ping reply coming from:________________ What is the amount of time each ping takes:_______________ Unfortuneately, Windows ping is in milliseconds only. What are the Min, Max, and Average times:____________________________ Ping the IPv4 loopback address. Any difference in the ping times:________ Ping by IP address. Any difference in the ping times:________ Anything sent to localhost or the loopback device never leaves the computer. Pinging localhost works even if not connected to the network. localhost, loopback address, and host's own IP address are all the same computer/NIC. Second question you need to ask yourself as you track down a networking or connectivity problem: 2. Can the computer communicate with another computer on the LAN with TCP/IP? Ping your neighbor's computer by its IP address (ask your neighbor what his/her IP address is): ___________________ If your neighbor's computer doesn't respond (personal firewall can be set to not respond to incoming pings), then ping your instructor's computer at 10.202.11.152 (Wait for second "Request timed out." before terminating ping command because often the first ping fails.) What is the amount of time each ping takes:_______________ What are the Min, Max, and Average times:____________________________ Roughly how many times faster is pinging the localhost than pinging your neighbor:___________ Ping the Macs. What is the average time:___________ Windows 8/10 Firewall allow ping: Control Panel | Windows Firewall | Advanced settings | Inbound | New Rule | ... Rule Type: Custom | Protocols & Ports | Protocol Type: ICMPv4 | ... ICMP Settings Customize | Specific ICMP types Echo Request. | Next Next Next... Name it maybe "ping request" Use the -l option of ping to specify the size in bytes of the dummy data that ping sends out in its message. ping the same host in our network that you pinged before but include 50000 bytes (50KB) as the data size. What is the average ping time for it now:_____________ The default data size is 32B. Ping the default gateway by its IP address. What is the amount of time each ping takes:_______________ What are the Min, Max, and Average times:____________________________ How does pinging the default gateway compare with pinging your neighbor,timewise:_______________ The default gateway is in the same network as your neighbor. IP addresses starting with 192.168. and 10. are special "unregistered" addresses for private internal networks not directly accessible from the Internet. These computers are "hidden" from the Internet by the router/default gateway which does a translation to and from the 192.168 or 10. address to an Internet-accessible "registered" IP address (this process is called NAT: network address translation). Notice that all the IP addresses in our network start with 10.***. because that is the network portion of these IP addresses, the last 3 octets (24 bits) being the host portion. Third question in the progressive movement outward from localhost, to LAN, to internetwork. 3. Can the computer communicate with another computer on a different network (LAN) in the same organization? What is the IP address of the "farside" of the default gateway (its address in the adjoining network that it is connected to) 10.128.128.126 (maybe) Ping the farside of our default gateway. Average ping time:________________________________ Usually the same amount of time as pinging the nearside as it is the same device. All communication outside a LAN goes through the default gateway (a router). That was their first step, or "hop". From the default gateway the pings were sent into the internetwork, possibly making many hops (each hop is a router) before arriving at the IP destination. The replies came back to the default gateway from the internetwork and then were sent to you. Finally, do we have connectivity to the Internet: 4. Can the computer communicate with some computer on the Internet? ping 172.217.161.196 This is an IP address that has been assigned to some organization. What is the amount of time each ping takes:_______________ What are the Min, Max, and Average times:____________________________ Run: ping -? to see the list of possible switches/options for ping and find the one that will translate/resolve an IP address into its hostname (what is the switch:____) and rerun the above command to find the hostname of the host at that IP address:______________________________ Use the same switch to find the name of the 23.41.22.6:_______________ ping can ping by IP address or by DNS hostname. ping www.asia.umgc.edu What is the average ping time:_______ BTW, What's a long time to ping? ping www.cenpac.net.nr (if that doesn't work, try: dns1.cenpac.net.nr ) (If your ping is IPv6, put a -4 option in the command line.) nr is the country code for Nauru, an island nation out in the Pacific, What are the Min, Max, and Average times:____________________________ It's using a satellite microwave link, which are slow because of the uplink and downlink to the geosynchronous satellite. ping www.anadyr.org This is/was? in Siberia. Update: no longer in Siberia :( What are the Min, Max, and Average times:____________________________ These above two are about as far away as you can get in the Internet these days, a whole second or so away for the roundtrip. UPDATE: both are faster now than they used to be. :) and :( Some addresses don't respond to the ping request: ping www.troy.edu (which exists, and has an IP address) What is the result:_________________________ A DNS name is first translated to its IP address: a lookup request is sent to the DNS server to "resolve" the DNS name to its underlying real name, i.e. its IP address. Some addresses don't exist, so a ping request isn't sent: ping arfarf.asia.umgc.edu What is the result:__________________________ A DNS lookup was attempted, it failed to find that name, so the pings weren't sent (there was no IP address to send them to). ping your favorite website (not umgc.edu or davidwills.us) Its DNS name and IP address:_________________________ Copy and paste the tracert [Mac traceroute] to it: