DNS Servers

DNS in the UNC Computer Science Department

Reviewed by Murray Anderegg 02/27/2013

The department has two DNS (Domain Name Service) servers, for mapping internet hostnames to IP addresses.  The machine IP addresses and names are:

152.2.131.227 – Host charlotte.cs.unc.edu
152.2.131.228 – Host bristol.cs.unc.edu

As of January 9, 2013 the department’s DNS servers only answer queries about non-CS hostnames from machines on the wired CS networks. If you are on wireless or off-campus, you should use your Internet Service Provider’s DNS settings, which are usually provided via DHCP.  If you wish to add a backup DNS server, Computer Services provided the following list of DNS servers at the time that access to the department’s DNS servers was restricted:

If you find that your ISP does not provide reliable DNS service, here are some verified open DNS servers and the providers of the 

services. We've tested the Google and OpenDNS servers and have not seen any problems.

Free Public DNS Server

=> Service provider: Google

Google public dns server IP address:

• 8.8.8.8

• 8.8.4.4

=> Service provider:OpenDNS

OpenDNS free dns server list / IP address:

• 208.67.222.222

• 208.67.220.220

=> Service provider:Dnsadvantage

Dnsadvantage free dns server list:

• 156.154.70.1

• 156.154.71.1

=> Service provider:Norton

Norton free dns server list / IP address:

• 198.153.192.1

• 198.153.194.1

=> Service provider: GTEI DNS (now Verizon)

Public Name server IP address:

• 4.2.2.1

• 4.2.2.2

• 4.2.2.3

• 4.2.2.4

• 4.2.2.5

• 4.2.2.6

This list was obtained from:http://theos.in/windows-xp/free-fast-public-dns-server-list/

Most machines now receive their DNS configuration when they boot, via the Dynamic Host Configuration Protocol (DHCP).  The information in the remainder or this document is intended for machines with a static configuration, and for debugging purposes.

Host charlotte is the primary server, bristol is the secondary server, and the primary nameserver should be listed first.  Clients normally query their DNS servers in very quick succession in case the primary server is unavailable.

Different operating systems and different network configurations define DNS servers in different places.   Below is information on some of the common places and configurations for DNS configuration supported in the Computer Science Department.  Always use the IP address when configuring the DNS servers, not the hostnames!

Linux and other non-Macintosh UNIX machines:

Most unix machines define the nameservers in a file called:

/etc/resolv.conf

This file should contain the addresses above.

Sample /etc/resolv.conf:

search cs.unc.edu
domain cs.unc.edu
nameserver 152.2.131.227
nameserver 152.2.131.228
nameserver 152.19.240.8

On Windows 7:

In the Control Panel, click Network and Sharing Center
On the right side fairly near the top, click Local Area Connection
Click Details

If it says “Yes” next to “DHCP Enabled, your machine is getting an IP address and DNS information from our DHCP server.

On Windows XP:

Right mouse click on My Network Places
Left mouse click on Properties
Right mouse click on the network connection you want to change (e.g. Local Area Connection)
Left click on Properties
Select TCP/IP Protocol
Click the Properties Button

If the “Obtain an IP address from DHCP server” is selected, your machine is getting an IP address and DNS information from our DHCP server.

Click the Advanced button.
Click on the DNS tab.

If the DNS Server Addresses box contains an IP address, make sure the address is for one of the two DNS servers listed above.  Manual entries in this area will overide the DHCP configuration supplied by the server.

On Macintosh:

In System Preferences, choose Networking, and then select the interface you wish to use.  Then use the Advanced button to reveal the advanced settings, and enter the IP numbers of the DNS servers in the DNS tab.