Most of the time, your ISP automatically assigns a primary and secondary DNS server when your router or computer requests network information via DHCP. But what if those ISP-provided DNS servers aren't reliable or you're troubleshooting an issue and you suspect that DNS might not be working properly?

Luckily there are several free DNS servers that you can use instead of the ones assigned to you.  

Free & Public DNS Servers (Updated May 2013)

[1] The DNS servers listed above as Level3 will automatically route to the nearest DNS server operated by Level3 Communications, the company that provides most of the ISPs in the US their access to the Internet backbone.

[2] Google also offers IPv6 public DNS servers: 2001:4860:4860::8888 and 2001:4860:4860::8844.

[3] Securly's DNS servers block adult content by default, including of course X-rated content but also adult oriented pages on websites like Wikipedia, adult themed searches on Google, and more. The grown-ups in the house can sign up here to bypass all restrictions.

[4] OpenDNS also offers DNS servers that block adult content, called OpenDNS FamilyShield. It's also free but you do have to sign up here. A premium DNS offering is also available, called OpenDNS Home VIP.

[5] The Norton ConnectSafe DNS servers listed above block sites hosting malware, phishing schemes, and scams. Use 198.153.192.50 and 198.153.194.50 to block those sites plus those with pornographic content. Use 198.153.192.60 and 198.153.194.60 to block all previously mentioned site categories plus those Norton deems "non-family friendly."

[6] ScrubIT also offers "filtered" DNS servers that restrict access to pornographic and malicious web sites. Those DNS servers are 67.138.54.100 and 207.225.209.66 and you can read more about it here.

[7] Register here with SafeDNS for content filtering options in several areas.

[8] DNSResolvers.com says they do not "alter" the traffic in any way, including correcting "typos and non-existent domains."

[9] The DNS servers listed here for OpenNIC are just two of many in the US and across the globe. Instead of using the OpenNIC DNS servers listed above, see their complete list of public DNS servers here and use two that are close to you or let them tell you that automaticallyhere. OpenNIC also offers some IPv6 public DNS servers.

[10] These Public-Root DNS servers are the only two currently operating in the United States but if you're located ouside the US, see their complete list here and choose the best servers based on your location.

[11] The censurfridns.dk DNS servers are uncensored, operated by a privately funded individual, and are physically located in Denmark. You can read more about them here. IPv6 DNS servers are also available at 2002:d596:2a92:1:71:53:: and 2002:5968:c28e::53

[12] Hurricane Electric also has an IPv6 public DNS server available: 2001:470:20::2.

[13] puntCAT is physically located near Barcelona, Spain. The IPv6 version of their DNS server is 2a00:1508:0:4::9.

Note: Primary DNS servers are sometimes called preferred DNS servers and secondary DNS servers are sometimes called alternate DNS servers. Primary and secondary DNS servers can be "mixed and matched" to provide another layer of redundancy.

We have become aware of a critical security vulnerability in very commonly used plug-ins for the popular WordPress blogging platform that present a risk to our customers. All customers using WordPress with either the W3 Total Cache plug-in or the WP Super Cache plug-in are encouraged to update their plug-ins as soon as possible. This upgrade is necessary even if the plug-in is installed but not currently active. WordPress plug-ins can be easily updated from within the WordPress admin interface's plug-in section. If you require assistance with this please contact our support team via http://support.carolinanet.com or by phone at (888) 400-5557 during business hours.

When making a password decision make sure your password is unique and can’t easily be detected. Here’s a great story about the 25 most common passwords of 2012 you should read http://www.cbsnews.com/8301-205_162-57539366/the-25-most-common-passwords-of-2012/

Your web based Voicemail access at http://manage.carolinadigitalphone.com needs to have a secure password so unwanted lookers can’t see, or listen to your voice mail messages. More important if someone does hack into your voicemail a smart user can make calls, or redirect calls from your desktop phone and look like they are you.

To change your web password login with your current username and password and click on Preferences where you will see Password Change.

If you have a question to how to change your password call 611.

November 1, 2012 6:00 PM EST Update:

Update from our upstream carriers today that all inbound calling issues were resolved last night around 1:30 AM EST.

I was told that the cause of the intermediate outages was caused by carriers in the North East routing call traffic to Southern United States switches causing an overload. This caused excessive post dial delay on calls in the Atlanta, Georgia and Birmingham, Alabama switch sites were we are services from.

Additionally there was a major fiber outage with some of the major carriers causing additional damage to the already overloaded network. Many AT&T (land and cell phone) customers could not make calls to anyone randomly during the day. We feel this issue has also been resolved.

At no time did we experience any problems with outbound calling. We use a diverse number of carriers including one on the west coast to deliver calls for our customers.
If you are still having problems with inbound calls please open a support ticket at this web site http://support.carolinadigitalphone.com

During this time we appreciate your patience and co-operation and appreciate your business.

October 31, 2012 1:30 PM EST: Update For Carolina Digital Phone Service Customers: 

We have experienced some random inbound calling issues that may impact your business this week. Our carriers have found some calling from cell phones, specifically from the AT&T network are getting busy signals when calling Carolina Digital Phone customers. This issue has been reported to our upstream carriers and as expected during a major disaster such as the East coast has now experienced, there is no estimated time to repair or remedy the problems at this time.

October 30, 2012: For Carolina Digital Phone Service Customers:

Please be advised that due to the impending adverse weather conditions in the Mid-Atlantic and North East telephone services may experience downtime. At this time we don't know if, or how long, any services will be impacted. Numbers that might experience an outage are telephone numbers originating in the Mid-Atlantic and North East states or any Toll-Free number in the United States or Canada. Or primary carrier for Toll-Free numbers is based in Pittsburgh, Pennsylvania. Areas of major impact include: Northern Virginia, Washington DC, Delaware, New Jersey, Pennsylvania, Eastern Ohio, New York, and Connecticut.  

A second outage you might experience would be if you are trying to call anyone in the Mid-Atlantic or North East states. The message you might hear would be 'all circuits are busy' or a very long delay and then possibly a busy signal. 

In line with our goal to provide you with the highest level of service possible, our team will be working diligently to ensure that all service delays are reported to carriers quickly and updates posted. During this time we really appreciate your patience and co-operation. If you experience a situation that needs our assistance please open a support ticket at http://support.carolinadigitalphone.com.

Updates will be posted at http://tinyurl.com/CarolinaDigitalPhoneNotices

UPDATE: October 31, 2012

We have been informed from one of our Origination providers that they are experiencing an outage due to Hurricane Sandy. This is affecting inbound calls at this time in the affected areas are listed below. As expected, there is no ETR at this time. We will provide updates as they become available. At present, we are not aware of any other carriers of ours being affected by the storm.

Burlington, VT
New York City, NY
Poughkeepsie, NY
Pleasantville, NJ
Harrisburg, PA
Scranton, PA
Roanoke, VA
Culpeper, VA
Norfolk, VA
Cleveland, OH
Worthington, OH
South Bend, IN
Bloomington, IN
Appleton, WI
Chicago, IL
Asheville, NC
Wilmington, NC
Charleston, SC
Augusta, GA
Macon, GA
Pensacola, FL
Orlando, FL
Mansfield, OH
Charlottesville, VA
Fayetteville, NC
Johnson City, TN
Newark, NJ
Philadelphia, PA
Pittsburgh, PA
Washington, DC

Cisco announces the end-of-sale and end-of-life dates for the Cisco PAP2T Internet Phone Adapter with 2 VoIP Ports. The last day to order the affected product(s) is May 16, 2012. Customers will continue to receive phone support from the Cisco Small Business Support Center (SBSC) as shown in Table 1 of the EoL bulletin. Table 1 describes the end-of-life milestones, definitions, and dates for the affected product(s). Table 2 lists the product part numbers affected by this announcement. For customers with active product warranties, support will be available as stated in the product warranty terms and conditions, even if this date exceeds the Last Date of Support shown in Table 1. The Cisco Takeback and Recycle program helps businesses dispose properly of surplus products that have reached their end of useful life. The program is open to all business users of Cisco equipment and its associated brands and subsidiaries. For more information, go to: http://www.cisco.com/web/about/ac227/ac228/ac231/about_cisco_takeback_recycling.html.

For more information about the Cisco SPA112 2 Port Phone Adapter, visit http://www.cisco.com/en/US/products/ps11977/index.html, or contact your local account representative.

The complete End of Life Announcement can be found http://www.cisco.com/en/US/prod/collateral/voicesw/ps6790/gatecont/ps10024/ps10029/end_of_life_notice_c51-700465.pdf