The Domain Name System

12-02+DNS+The+Domain+Name+System (1).pdf

(DNS) resolves a fully qualified domain name (FQDN) such as www.cisco.com to an IP address

Enterprises usually have their own DNS Server to resolve internal hosts.

Hosts will send their DNS queries to the server.

If internal DNS cannot resolve the query, it would forward the request out to public DNS servers on the internet.

DNS requests are sent using DUDP port 53 (and can fail over to TCP)

DNS on Cisco Routers

12-03+DNS+on+Cisco+Routers.pdf

DNS Client: ip domain-lookup ip name-server 172.23.4.1 ip domain-name Dnsnameserver1.lab ip domain-list Dnsnameserver2.lab

Aditional DNS server commands

IP dns server ip host LinuxA 172.23.4.2