Delegated Mode
When executes in representation mode, requests are transferred or steered again to the BIG-IP DNS for Wide IP resource logs.
Screening Mode
BIG-IP DNS takes position in front of one or more DNS server when scanning mode is executing. This configuration provides easy implementation of additional BIG-IP system features for DNS traffic. Because DNS requests which exist for logs that out of Wide IP’s, pass from BIG-IP DNS.
If request pairs with Wide IP, BIG-IP response to the DNS request. Otherwise, request is sent to the DNS servers. This configuration provides advantages that listed below:
- DNS query validation: BIG-IP DNS verifies that query was well-created when one request arrives to the BIG-IP DNS. It can prevent back-end DNS servers to see wrong designed queries with leaving wrong queries.
- DNSSEC dynamic signing: It’s possible for BIG-IP DNS to sign response when responses on DNS server turn back over BIG-IP DNS.
- Transparent caching: The responses on DNS server can take response to the cache when they pass through BIG-IP system. Requests that intended to the new logs can be provided from BIG-IP system with directly reducing the load on back-end DNS servers in future.
Replacing a DNS Server
It is possibile that Big-IP can also work as an independent and authorized DNS server for one or more regions. All DNS requests are sent to BIG-IP DNS for a region. Any request for Wide-IP, is handled from BIG-IP DNS and other requests are sent to the local bind in BIG-IP system.
iQuery is a XML protocol that BIG-IP systems use it for making connection between themselves. BIG-IP DNS use iQuery for different duties:
- Determination of object’s health in BIG-IP DNS configuration.
- Making information exchange about the condition of BIG-IP DNS synchronization group
- Providing a transfer for synchronizing BIG-IP DNS configuration during equalization group.
- Sending LDNS way scanning metrics.
- Exhanging Wide IP persistence information.
- Aggregating BIG-IP system configuration during the usage of auto discovery.
All these integrated duties provide BIG-IP DNS configuration and BIG-IP DNS synchronization group that represents condition of integrated view.