Dual Stack (IPv4 & IPv6)

Introduction to Dual Stack

• Simultaneous use of IPv4 & IPv6
• Host will have multiple IPs
  • Private IPv4
  • Link-Local IPv6
    • FE80 messages - you can do discovery of other services.
  • Random IPv6
    • Constantly changes (Microsoft changes it for your privacy)
  • Deprecated random IPv6

Dual Stack Operations

• IPv6 preferred to IPv4
• Ethernet doesn't mind
• TCP doesn't seem to care
• DNS is identical from user perspective
• Easy
  • Firewall rules
  • Routing table
  • ACLs
  • Application support

Dual Stack Addressing

10.1.100.13/24
10.1.100.1 gateway

2001:ABCD:4321:100::13/64
2001:ABCD:4321:100::1 gateway

DNS Records

• A records reference IPv4 addressing
• AAAA records reference IPv6 addressing
• DNS Services on UDP 53 - TCP - Zone XFER
  • BIND listening on port UDP 53
  • Is the socket associated to this process, and is processing this queries.
    • Doesn't matter if it is an IPv4 response (A)
    • Doesn't matter if it is an IPv6 response (AAAA)
• DNS Services run on IPv4 or IPv6