1. © F5 Networks, Inc. 1 How Does DNS Work? http://www.domain.com A user browses to www.domain.com www.domain.com A user browses to www.domain.com www.domain.com LDNS Root DNS Server (one of 16 from root.hints) Is there a record for www.domain.com? Go ask.com.com DNS Server Is there a record for www.domain.com? Go ask domain.com The LDNS asks.com for www.domain.com, which returns an NS record for domain.com www.domain.com The LDNS asks.com for www.domain.com, which returns an NS record for domain.com www.domain.com The LDNS asks domain.com for www.domain.com, which returns an A record www.domain.com The LDNS asks domain.com for www.domain.com, which returns an A record www.domain.com Is there a record for www.domain.com? 66.163.171.129 domain.com DNS Server

2. © 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? 66.163.171.129 Web Server http://www.domain.com Is there a record for www.domain.com? The browser opens a connection to address:80 and does a GET /… … And the server returns the Web page response 66.163.171.129 The LDNS returns the A record to the client and caches it locally 66.163.171.129

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

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

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

6. © F5 Networks, Inc. 6 DNS Delegation Sample Configuration Example database prior to delegation: www.domain.com. IN A 200.10.10.10 www.domain.com. IN A 150.10.10.10 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 200.10.10.53 gtm2.wip.domain.com. IN A 150.10.10.54 www.domain.com. IN CNAME www.wip.domain.com.

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

8. © F5 Networks, Inc. 8 GLSB and Delegation Mode http://www.company.com LDNS Is there a record for www.company.com? Data Center BIG-IP Global Traffic Manager company.com DNS Server www.gtm.company.com 66.163.171.129 X 72.68.171.103 Is there a record for www.gtm.company.com?

9. © F5 Networks, Inc. 9 BIG-IP DNS Authoritative Screen LDNS www.subzone.company.com 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 www.gtm.company.com 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

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

11. © 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 73.37.1.1:80 Virtual Server 68.28.1.1:80 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 73.37.1.11:21 Virtual Server 205.33.1.1:80 Virtual Server Wide IP: www.f5.com = 73.37.1.1 or 68.28.1.1 or 205.33.1.1