5B troubleshooting Windows Network
ipconfig all/
-displays more detailed -DHCP DNS server MAC address and NetBIOS status
Security layer
-firewall,software, or hardware could be blocking connection
Troubleshoot Local Network Connectivity
-if link and IP configuration both are correct, the problem may not be the PC but instead with the network topology itself - see if you can test servers such as file shares printer or email by using them **this method means it could be an application fault rather than a network fault**(doesn't really isolate the problem well) -Better to have a low level test of basic connectivity that doesn't depend on anything but a working link and IP configuration
Troubleshoot Name Resolution
-if you cannot locate the problem with basic connectivity problem could be at higher layer of processing 3 additional layers where network service fail -Security -Name resolution -application/OS
netstat command
-investigate open ports and connections on the local host -verify whether file sharing or email ports are open on a server and whether other clients are connecting to them -active and listening TCP ports
ping 127.0.0.1
-pinging loop back address to verify TCP/IP is installed and loaded correctly
DHCP lease missing or incorrect, request a new one
-release current IP for network adapters ipconfig /release AdapterName -force DHCP client to renew the lease it has for an IP address ipconfig /renew AdapterName
hostname Command
-returns name configured on local machine hostname * if the machine is a server, clients will need to use the hostname to get access to shared folders and printers
Ping command
-test host to host communication within same network or remote network 1. ping loop back addy (127.0.0.1) reserved loop back address 2. ping yourself 3.ping your router 4.ping target remote host
tracert
-trace the path of a packet to its destination -takes Ip address or FQDN as argument [IN THE PICTURE] *first probe is for the hosts router *second probe is for the destination address public Internet routers and servers ** a timeout could mean failure or that destination router is set to not to respond to probes
Network Reset
-use if network problems persist with client or server - restart computer hardware or application service **consider impact on users if you do this kinda of a last ditch effort
No internet access State
-valid for local network, but windows cannot identify a working connection - attempt to connect to www.msftncsi.com and checking to see if DNS resolves the IP correctly -Indicates problem with router, DNS or BOTH
Ping Default Gateway(Router)
-verify router is up and running -verify communication between hosts on local network
Ping remote Host IP
-verifying communication to remote host via the router
ipconfig
Displays ip address, subnet mask, default gateway (router) for all network adapter bound to TCP/IP
You are pinging a host at 192.168.0.99 from a host at 192.168.0.200. The response is "Reply from 192.168.0.200: Destination host unreachable." The hosts use the subnet mask 255.255.255.0. Does the ping output indicate a problem with the default gateway?
No. The hosts are on the same IP network (192.168.0.0/24). This means that 192.168.0.200 does not try to use a router (the gateway) to send the probes. 192.168.0.200 uses address resolution protocol (ARP) to find the host with the IP 192.168.0.99. The host unreachable message indicates that there was no response, but the problem will be an issue such as the host being disconnected from the network or configured to block discovery rather than a gateway issue.
netstat -b
Shows the process that has opened the port
A computer cannot connect to the network. The machine is configured to obtain a TCP/IP configuration automatically. You use ipconfig to determine the IP address and it returns 0.0.0.0. What does this tell you?
This is an irregular state for a Windows PC. If a DHCP server cannot be contacted, the machine should default to using an APIPA address (169.254.x.y). As it has not done this, something is wrong with the networking software installed on the machine. The best option is probably to perform a network reset via the Settings > Network & Internet > Status page.
Which command produces the output shown in this screenshot?
This is output from netstat. The -n switch has been used to show ports in numeric format and the -o switch to show the PID of the process that opened the port.
Ping Ip Address of your workstation
- Verifies it was added correctly -check for duplicate IP addressing issue
netstat -e netstat -s
can be used to report Ethernet and protocol statistics respectively.
netstat -a
includes UDP ports in the listening state.
A DHCP server has been reconfigured to use a new network address scheme following a network problem. What command would you use to refresh the IP configuration on Windows client workstations?
ipconfig /renew
netstat -o
list the process ID (PID)
netstat -n
- displays ports and addresses in numerical format *Skipping name resolution speeds up each query.
Name resolution
-DNS server might be out so connecting by the name of the website may not work -connecting via IP address may be possible if the DNS server is not working
Resolve DNS issue via ipconfig
-Display DNS resolver cache containing host and domain names recently queried ipconfig /displaydns -Clears the DNS resolver cache. If cached records are out-of-date, it can cause problems accessing hosts and services ipconfig /flushdns
Host cannot be located
-If host can't be located, the hops that were passed through will still be shown -shows which interface on each router received request and response time - (*) shown on a router with no response at all in the route
Application/OS
-OS failure may result in no connectivity to host server -server can be contacted but not specific service, the service process might have crashed
nslookup -Option Host Server
-Option specifies a nslookup subcommand -Host can be either a host name/FQDN or an IP address -Server is the DNS server to query
Successful Ping
-Replies with message reply from IP address with its response time
ping Unsuccessful
-SenderIP destination unreachable : sending host gets no response to ARP probes. If target is confirmed up, then it is either not connected or configured as non-discoverable -GatewayIP destination unreachable: no forwarding information for that IP address, Indicates IP misconfig -No reply (request timed out) : sent
Troubleshoot IP configuration
-Several error states types Is connection unplugged or plugged? -most start with investigating IP configurations current settings -use ipconfig command tool to view information of current configurations
Troubleshooting remote network connectivity
-a hop is each router passed in the network from the source to the destination IP -
pathping
-a little deeper ping probe -perform trace but pings each router hop a set amount of times to determine the RTT to measure the latency more accurately -shows packet loss at each hop
Limited connectivity State
-adapter is set to obtain address automatically but no DHCP server can be contacted - Adapter will use an address from the automatic IP addressing(APIPA) 169.254.x.y range -or will use and alternate IP that was configured specifically as an alternate
Routing issues
-check local router status -check ISP service status page for a widespread outage -check DNS outtages -reset router
Reset the network stack on a device
-clears custom adapter configs and network connections including VPN connections ** will have to be reconfigured after you reset -can be done through Settings ? Network and Internet >Status Page
the following command queries Google's public DNS servers (8.8.8.8) for information about comptia.org's mail records
nslookup -type=mx comptia.org 8.8.8.8
You are checking that a remote Windows workstation will be able to dial into a web conference with good quality audio/video. What is the best tool to use to measure latency between the workstation's network and the web conferencing server?
pathping measures latency over a longer period and so will return a more accurate measurement than the individual round trip time (RTT) values returned by ping or tracert.
Ping DNS
ping comptia.org - ping DNS ping sales.comptia.org - ping FQDNs *wont work if DNS server is unavailable
Round Trip Time (RTT)
the time it takes for a small packet to travel from client to server and then back to the client
