© F5 Networks, Inc. 1 How Does DNS Work? A user browses to A user browses to LDNS Root DNS Server (one of 16 from root.hints) Is there a record for Go ask.com.com DNS Server Is there a record for Go ask domain.com The LDNS asks.com for which returns an NS record for domain.com The LDNS asks.com for which returns an NS record for domain.com The LDNS asks domain.com for which returns an A record The LDNS asks domain.com for which returns an A record Is there a record for domain.com DNS Server

© F5 Networks, Inc. 2 LDNS Root DNS Server (one of 16 from root.hints).com DNS Server domain.com DNS Server How Does DNS Work? Web Server Is there a record for The browser opens a connection to address:80 and does a GET /… … And the server returns the Web page response The LDNS returns the A record to the client and caches it locally

© F5 Networks, Inc. 3 General Use Cases for DNS Delegation LDNS DNS Server LDNS requests LDNS requests CNAME to CNAME to DNS Server returns an A record with the IP address of the desired resource returns an A record with the IP address of the desired resource LDNS requests LDNS requests

© F5 Networks, Inc. 4 DNS Load Balancing with LTM (No GTM) LDNS Data Center DNS Servers company.com LDNS requests LDNS requests LTM responds with the DNS A record LTM passes the request to the DNS server pool The DNS server responds with an A record IP for The DNS server responds with an A record IP for BIG-IP Local Traffic Manager i A DNS iRules* IP Anycast* A i *Requires DNS Services Add-on

© F5 Networks, Inc. 5 Data Center BIG-IP Global Traffic Manager company.com DNS Server GSLB and Delegation Mode LDNS Root DNS Server Is there a record for Go ask.com.com DNS Server Is there a record for Go ask company.com Is there a record for Return CNAME

© F5 Networks, Inc. 6 DNS Delegation Sample Configuration Example database prior to delegation: IN A IN A Example database after delegation: wip.domain.com. IN NS gtm1.wip.domain.com. wip.domain.com. IN NS gtm2.wip.domain.com. gtm1.wip.domain.com. IN A gtm2.wip.domain.com. IN A IN CNAME

© F5 Networks, Inc. 7 GSLB and Delegation Mode LDNS Is there a record for Go ask.com Is there a record for Go ask company.com Is there a record for Root DNS Server.com DNS Server Data Center BIG-IP Global Traffic Manager company.com DNS Server

© F5 Networks, Inc. 8 GLSB and Delegation Mode LDNS Is there a record for Data Center BIG-IP Global Traffic Manager company.com DNS Server X Is there a record for

© F5 Networks, Inc. 9 BIG-IP DNS Authoritative Screen LDNS DNS Server Data Center company.com LDNS send a DNS query BIG-IP GTM/LTM-DNS Services Resolved DNS request If GTM is enabled, check GTM Wide IPs and if matched, resolves to the best IP DNS Listener on the BIG-IP receives all DNS requests Else, forward the query to external DNS servers If DNS Express is enabled, check against DNS Express zones and then local BIND

© F5 Networks, Inc. 10 BIG-IP DNS Authoritative Screen LDNS DNS Server Data Center company.com Q X i DNS Express DNSSEC Geolocation DNS iRules X Q i BIG-IP GTM/LTM-DNS Services

© F5 Networks, Inc. 11 GTM Pool Wide IP (WIP) objects Fully Qualified Domain Names (FQDNs) associated with one or more pools Wide IP (WIP) objects Fully Qualified Domain Names (FQDNs) associated with one or more pools Objects in the GTM Architecture Primary DC Secondary DC Disaster Recovery DC GTM LTM Server :80 Virtual Server :80 Pool objects Groups of virtual servers to be load balanced Pool objects Groups of virtual servers to be load balanced Virtual servers objects IP address:port combinations on server objects Applications to load balance/resolve too May represent multiple real servers (load balancers) Or a single physical (standalone) server Server objects often host multiple virtual servers Virtual servers objects IP address:port combinations on server objects Applications to load balance/resolve too May represent multiple real servers (load balancers) Or a single physical (standalone) server Server objects often host multiple virtual servers :21 Virtual Server :80 Virtual Server Wide IP: = or or