Configure This – Ipconfig Commands And Uses

Many people are familiar with the command (commonly abbreviated cmd) prompt that is on their Microsoft Windows OS. From here you can run a variety of commands that will display various tidbits of information. One of the most commonly used command prompts is the ‘ipconfig‘ prompt.
Now, once you are on your cmd screen simply type in “ipconfig” and you should get something similar to this below:

Other ipconfig commands
– Ipconfig /?
This will display a whole plethora of information because the ? makes it a help message.
– Ipconfig /all
This will display all of your configuration information.
– Ipconfig /renew
This will renew the IPv4 address for your adapter.
– Ipconfig /release
This will release the IPv4 address (you can renew it afterwards).
– Ipconfig /release 6
This does the same as the previous release except it targets the IPv6 address.
– Ipconfig /allcompartments
Just a command that will show you all of the information on all compartments.
– Ipconfig /flushdns
Flushdns will purge the DNS resolver cache.
– Ipconfig /registerdns
This will refresh all DHCP leases and will re-register the DNS names.
– Ipconfig /displaydns
This is how you display all of your DNS information.
– Ipconfig /showclassid
Showclassid will display all of your dhcp class ID’s that are allowed for the adapter.
– Ipconfig /setclassid
Using this prompt will modify the dhcp class ID.
– Ipconfig /showclassid6
This will display all of the IPv6 DHCP class ID’s allowed.
– Ipconfig /setclassid6
This will modify the IPv6 DHCP class ID.

What are the ipconfig commands used for?
When you are having internet connection issues, one of the most common places to check for the problem is your adapter settings. Using ipconfig commands gives you the ability to assess your connections, renew them, and gather vital information that could aide you in successfully repairing your internet connection.

You can also use the ipconfig commands (specifically ones pertaining to the DNS) to resolve some common errors that you may encounter. If your DNS cache is outdated or corrupted in any way while browsing the internet you can have difficulty accessing the sites that became corrupted in your cache.

One such scenario would be you trying to access a site that was down, but then it came back up later. If your DNS cache got corrupted it will save the information on the site being down even though the site is now updated and back online. Due to that corruption you will still see the site as ‘down’. A way to fix this is by flushing your DNS and retrying the site.

As soon as you experience internet connection troubles with your computer you should first check to see if your router is online, WiFi is on, then you go to your cmd prompt. These are common issues that many people face and it is a quick fix for internet problems that often lead to hours of frustration.

What is Dynamic DNS ? A Brief Look At Dynamic DNS

Dynamic DNS(Domain Name System) is an extension to DNS, that allows to update the IP address of a domain in real time. In the internet world, domain names resolve to IP addresses.
Eg: When someone visits, the browser hits a DNS server to resolve the domain name to IP address. Once a connection is established, further subsequent calls will take place to and forth.

In common mans term, DNS servers can be assumed to be a phone book for the internet, where if know a persons name, we can get access to the details of the person. Without DNS decoding, users would be forced to enter the actual IP address ( instead of domain nomain (, which is an alias to the IP address in reality.

You can read more about Dynamic DNS here.

Dynamic DNS can be setup on any computer server with minimum setup requirments, ie. changing the maximum caching time or the time intervas between caching of a domain, to a very short period. The time could be set between one to two minutes. Thus preventing storage of IP address, allowing visitors to a particular site to update their old information by contacting the name server on successive visit.

Dynamic DNS has its footprint in home server marketplace. Soon this method or protocol is gaining momentum with the computer technology and increasing speed in internet. Today, numerous providers called Dynamic DNS service providers, offer such technology and services on the internet.

Microsoft Windows networks offers it as an integral part of Active Directory, because domain controllers register their network service types in DNS so that computers in the Domain (Forest) can access them.

[What is Dynamic DNS?].

How do I flush DNS in Windows, Mac and Linux ?

When do you want flush DNS?

You visit one of the most frequently viewed websites in your list and find it’s not loading up, it could be very frustrating at times.

The site can be down for more than one reason, the most common one being, the remote server being down. To ensure if the server is up, ping the server directly, and the response tells you the status.

Let’s assume that the servers working fine, but still the site does not load up in your browser! DNS failure can be the cause. And this us a common case if server is relocated and/or the site is moved on to a new server, as DNS propagation normally takes anywhere from 24 – 72 hrs to propagate and work fine.

This scenario is also true when you set up new domain on a server.

If the site fails to show up even after 72 hrs, you may have to clear your DNS cache to ensure the request is not going to the old ips of the site you are trying to load.

Clearing DNS cache will ensure your PC does not have old records of bad DNS entries.If the bad entries are not flushed then you need to wait up to 24 hours for it to be dropped from the cache automatically, which is a scheduled activity in some computers.

The following list gives you the set of commands to flush DNS on different platforms:

If you are on Microsoft Windows:

1. Use the command ipconfig/flushdns in your command prompt.

2. The ipconfig/displaydns can be used to view the DNS resolver cache.

If you wish to turn off DNS Caching on Microsoft windows then The client-side DNS caching can be disabled by using either of these two commands:

1. net stop dnscache

2. sc servername stop dnscache

Until the next reboot DNS caching will be disabled and to make this permanent user the Service Controller tool or the Services tool to disable DNS Client service startup type.

If you use Mac OS X Leopard:

1. Use dnscacheutil -flushcache

Eg: bash-2.05a$ dnscacheutil -flushcache

And if you are on any version of Linux:

1. Use nscd daemon which manages the DNS cache.

Restart the nscd daemon by using the command ‘/etc/init.d/nscd restart