Viewing the current DNS configuration
The
show ip
command displays the current domain suffix and the IP address of the highest priority DNS server
configured on the switch, along with other IP configuration information. If the switch configuration currently
includes a non-default (non-null) DNS entry, it will also appear in the
show run
command output.
Figure 101: Example: of viewing the current DNS configuration
Operating notes
• Configuring another IP address for a priority that has already been assigned to an IP address is not allowed.
To replace one IP address at a given priority level with another address having the same priority, you must first
use the no form of the command to remove the unwanted address. Also, only one instance of a given server
address is allowed in the server list. Attempting to enter a duplicate of an existing entry at a different priority
level is not allowed. To change the priority of an existing server address, use the no form of the command to
remove the entry, then re-enter the address with the new priority.
• To change the position of an address already configured with priority
x
, you must first use
no ip dns
server-address priority x
<ip-addr>
to remove the address from the configuration, then use
ip
dns server-address priority
<ip-addr>
to reconfigure the address with the new priority. Also, if the
priority to which you want to move an address is already used in the configuration for another address, you
must first use the
no
form of the command to remove the current address from the target priority.
• The DNS servers and domain configured on the switch must be accessible to the switch, but it is not
necessary for any intermediate devices between the switch and the DNS server to be configured to support
DNS operation.
• When multiple DNS servers are configured on the switch, they can reside in the same domain or different
domains.
• A DNS configuration must include the IP address for a DNS server that is able to resolve host names for the
desired domain. If a DNS server has limited knowledge of other domains, its ability to resolve DNS-compatible
command requests is also limited.
• If the DNS configuration includes a DNS server IP address but does not also include a domain suffix, then any
DNS-compatible commands should include the target host’s fully qualified domain name.
• Switch-Initiated DNS packets go out through theVLAN having the best route to the DNS server, even if
aManagement VLAN has been configured.
• The DNS server address must be manually input. It is not automatically determined viaDHCP.
Chapter 13 Troubleshooting
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