Cisco Catalyst 9400 User Manual

DNS Customization
NBAR2 examines DNS request and response traffic, and can correlate the DNS response to an application.
The IP address returned from the DNS response is cached and used for later packet flows associated with that
specific application.
The command ip nbar custom application-name dns domain-name id application-id is used for DNS
customization. To extend an existing application, use the command ip nbar custom application-name dns
domain-name domain-name extends existing-application.
For more information on DNS based customization, see http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/
qos_nbar/configuration/xe-3s/asr1000/qos-nbar-xe-3s-asr-1000-book/nbar-custapp-dns-xe.html.
DNS Customization
Custom application called MYDNS using the DNS domain name “mydomain.com” with selector
ID 12.
Device# configure terminal
Device(config)# ip nbar custom MYDNS dns domain-name *mydomain.com id 12
Composite Customization
NBAR2 provides a way to customize applications based on domain names appearing in HTTP, SSL or DNS.
Composite Customization
Custom application called MYDOMAIN using HTTP, SSL or DNS domain name “mydomain.com”
with selector ID 13.
Device# configure terminal
Device(config)# ip nbar custom MYDOMAIN composite server-name *mydomain.com id 13
L3/L4 Customization
Layer3/Layer4 customization is based on the packet tuple and is always matched on the first packet of a flow.
L3/L4 Customization
Custom application called LAYER4CUSTOM matching IP addresses 10.56.1.10 and 10.56.1.11,
TCP and DSCP ef with selector ID 14.
Device# configure terminal
Device(config)# ip nbar custom LAYER4CUSTOM transport tcp id 14
Device(config-custom)# ip address 10.56.1.10 10.56.1.11
Device(config-custom)# dscp ef
Examples: Monitoring Custom Applications
Show Commands for Monitoring Custom Applications
show ip nbar protocol-id | inc Custom
Device# show ip nbar protocol-id | inc Custom
LAYER4CUSTOM 14 Custom
System Management Configuration Guide, Cisco IOS XE Bengaluru 17.4.x (Catalyst 9400 Switches)
203
Configuring Application Visibility and Control in a Wired Network
DNS Customization

Cisco Catalyst 9400 Specifications

General

Product Series	Catalyst 9400 Series
Layer	Layer 2/3
Operating System	Cisco IOS XE
Switch Type	Modular
Uplink Interfaces	10 Gigabit Ethernet, 40 Gigabit Ethernet, 100 Gigabit Ethernet
Stacking	No
Form Factor	Modular Chassis
Operating Temperature	0°C to 40°C (32°F to 104°F)
Redundancy	Power supplies
Security Features	MACsec
Management	Cisco DNA Center, CLI, SNMP