Cisco 6821 Administration Guide

Verify DNS Settings
Procedure
Step 1 On the phone, press Applications .
Step 2 Select Admin Settings > Network Setup > IPv4 Setup
Step 3 Check that the DNS Server 1 field is set correctly.
Step 4 You should also verify that a CNAME entry was made in the DNS server for the TFTP server and for the
Third-Party Call Control.
You must also ensure that DNS is configured to do reverse lookups.
Additional Troubleshooting Information
If you have additional questions about troubleshooting your phone, go to the following Cisco website and
navigate to the desired phone model:
https://www.cisco.com/cisco/web/psa/troubleshoot.html
Cisco IP Phone 6800 Series Multiplatform Phones Administration Guide
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Phone Troubleshooting
Verify DNS Settings

Cisco 6821 Specifications

General

Resolution	320 x 240 pixels
Speakerphone	Yes
Headset Port	Yes
Protocols	SIP
USB Port	No
Wireless	No
Bluetooth	No
Video Support	No
Conference Capabilities	Yes
Wall Mountable	Yes
Display	3.5-inch grayscale
Ethernet	10/100 Ethernet
Line Keys	2
PoE	IEEE 802.3af Power over Ethernet (PoE)
Codecs	G.711, G.722, G.729, iLBC
Weight	2.0 lb (0.91 kg)