Selective Assignment of a GSLB Service to DNS Virtual Services

Starting with release 17.2.3, the Avi CLI supports GSLB configurations that need to selectively assign DNS request-handling on a sub-domain basis to particular Avi DNS virtual services. With 17.2.5, support for this feature is extended to the Avi UI.

Use Case

Consider an environment with

  • DNS responsibility pushed to all DNS virtual services in the GSLB setup,
  • global services in multiple subdomains, and
  • application VIPs residing in separate routing domains.

The health checking Avi DNS SEs perform would necessarily require crossing routing-domain boundaries, which may be unacceptable.

The Avi Vantage alternative is to:

  • configure several GSLB DNS virtual services,
  • probably one per routing domain, and
  • selectively assign DNS request-handling on a sub-domain basis to the various Avi DNS VSs,
  • such that the VIP-serving SEs can reside in the same routing domain as the DNS VS that serves up their virtual IPs.

Avi CLI Configuration

Step 1. Using an ID having administrative privileges, login into the Avi shell of the GSLB leader’s Controller. Step 2. Invoke the configure gslb command, specifying the name of the configuration. For example: configure gslb Default Step 3. In response to the gslb prompt, keying in two tabs reveals the subcommands available to you:


[admin:topo1-controller]: gslb> 
cancel                 Exit the current submode without saving                                                                                            
clear_on_max_retries   Max retries after which the remote site is treated as a fresh start. In fresh start all the configs are downloaded.                
client_ip_addr_group   (submode)                     
description            Help string not found for argument                                                                                                  
dns_configs            (submode)                     
do                     Execute a show command        
is_federated           This field indicates that this object is replicated across GSLB federation.                                                         
leader_cluster_uuid    Mark this Site as leader of GSLB configuration. This site is the one among the Avi sites.                                           
maintenance_mode       This field disables the configuration operations on the leader for all federated objects.  CUD operations on Gslb, GslbService, GslbGeoDbProfile and other federated objects will be rejected. The rest-api disabling helps in upgrade scenarios where we don't want configuration sync operations to the Gslb member when the member is being u...
name                   Name for the GSLB object.     
new                    (Editor Mode) Create new object in editor mode                                                                                      
no                     Remove field                  
save                   Save and exit the current submode                                                                                                   
send_interval          Frequency with which group members communicate.                                                                                     
show_schema            show object schema            
sites                  (submode)                     
tenant_ref             Help string not found for argument                                                                                                  
third_party_sites      (submode)                     
view_id                The view-id is used in change-leader mode to differentiate partitioned groups while they have the same GSLB namespace. Each partitioned group will be able to operate independently by using the view-id.                                   
watch                  Watch a given show command    
where                  Display the in-progress object

Step 4. The sites sub-command gets invoked three times, once per DNS to be assigned:

Assigning DNS vs-1 to subdomain com
Figure 1. Assigning DNS vs-1 to subdomain com.


Assigning DNS vs-2 to subdomain edu
Figure 2. Assigning DNS vs-2 to subdomain edu.


Assigning DNS vs-3 to subdomain net
Figure 3. Assigning DNS vs-3 to subdomain net.


Step 5. Save the configuration:

GSLB save the site
Figure 4. GSLB save the site


Avi UI Configuration

Navigate to Infrastructure > GSLB > Site Configuration to view and/or set the settings related to the selective assignment of a GSLB service to DNS virtual services.

GSLB Site Configuration
Figure 5. GSLB Site Configuration.
Defining GSLB subdomains
Figure 6. Defining GSLB subdomains
Editing GSLB site_A
Figure 7. Editing GSLB site_A
Subdomain selection pulldown
Figure 8. Subdomain selection pulldown
Assigning subdomains to the DNS virtual services
Figure 9. Assigning subdomains to the DNS virtual services
Assigning subdomains to site B's DNS virtual services
Figure 10. Assigning subdomains to site B's DNS virtual services