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- [Instructor] In Windows,

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one of the first network troubleshooting tools

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you will use is IP config.

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It allows you to quickly verify IP information configured

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on network interfaces.

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I start by opening a command prompt.

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I can select start and type CMD

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and then hit enter. Typing IP config

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with no additional parameters shows me all

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of the network interfaces on my computer,

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along with IPV six addresses, IPV

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four addresses, sub-net mask and default gateway.

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Any interfaces that are unplugged show

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up as media disconnected.

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I'm going to go ahead and clear the screen.

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There is quite a bit more information that can be shown

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by typing IP config/all.

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This shows the same output as the previous command

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but also gives the physical address or Mac address

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for each interface, whether DHCP is enabled or not,

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when the DHCP and lease was obtained,

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and when it will expire. /all also

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lists the IP address

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of the DHCP and or manually configured DNS servers.

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If DHCP is enabled on my network

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there are additional control commands I can use

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with IP config.

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If there's an IP address assigned via DHCP to an interface

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IP config/release will remove it.

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By default, if I enter the command

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without specifying a specific interface

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it will release the DHCP leases assigned to all interfaces.

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I can use wildcards in the interface name to make it easier.

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These are simply asterix. On this machine

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I've got wireless land adaptor wifi, so I'll type

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IPconfig/release*FI.

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Once the IPS have been released, I can query

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for new ones by issuing IPconfig/renew.

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In this case, I'm just going to hit the

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up arrow and change my command to renew.

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Again, I can choose to specify an interface or not.

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For you IPV six lovers out there,

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IPconfig/release6 and IPconfig/renew6 will control

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V6 DCP IP addresses.

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There are also a few DNS commands

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that are great troubleshooting tools.

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I can flush the local DNS cache

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with IPconfig/flushDNS.

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Alternately if I want to view the DNS cache

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I can issue IPconfig/displayDNS.

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Display DNS shows each entry, the type of record

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that it is, be it a record or C name, it's TTL,

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and ultimately what it resolved to.

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An A record will be a direct DNS

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to IP mapping, where a C name is a DNS entry that points

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to another DNS entry for ultimate resolution.

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Linux isn't wholly different.

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To list the IP addresses present on the server

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I simply type IP ADDR.

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To view the routing table information

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like the default gateway

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the IP route command can be entered.

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These simple commands are used daily

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in the world of network support and administration.