A newly connected IPv6 host receives no DHCP response. It has no manually configured address. What does SLAAC allow it to do, and what two pieces of information does it combine to form its address?
AIt uses ARP to discover an available address on the subnet and claims it by broadcast
BIt generates a 64-bit interface ID and waits for a Router Advertisement containing the 64-bit network prefix, then combines the two into a 128-bit global unicast address
CIt falls back to a 32-bit IPv4-compatible address automatically converted to IPv6 format
DIt assigns itself a link-local address and waits indefinitely until a DHCP server appears
SLAAC (Stateless Address Autoconfiguration) is IPv6's plug-and-play address assignment mechanism. The host generates its own 64-bit interface ID (from its MAC address or randomly for privacy), listens for a Router Advertisement (RA) from the local router containing the 64-bit network prefix, and concatenates them to form a 128-bit global unicast address. It then runs Duplicate Address Detection via Neighbor Discovery to verify no other host already uses this address. No server is involved — hence 'stateless.'
Question 2 Multiple Choice
A packet is destined for fe80::c0a8:1. A router receives it. What should the router do?
ARoute it normally using the global routing table, since fe80::/10 is a publicly routable prefix
BDrop it or refuse to forward it — link-local addresses are only valid on the local network segment and are not routable beyond the link
CConvert it to an IPv4 address and forward using dual-stack
DForward it only if the destination is in the same /48 subnet
fe80::/10 is the link-local address prefix. Link-local addresses are assigned to every IPv6 interface automatically but are only valid for communication on the same local network segment (link). Routers must not forward packets with link-local source or destination addresses — they have no global meaning beyond the link. This is a common source of confusion: just because a device has an IPv6 address doesn't mean it is globally reachable. Only global unicast addresses (typically 2000::/3) are globally routable.
Question 3 True / False
In IPv6 compressed notation, the double-colon (::) abbreviation can be used only once per address to avoid ambiguity about how many zero groups are being replaced.
TTrue
FFalse
Answer: True
If two separate runs of all-zero groups could both be compressed to ::, the full address would be unrecoverable — you would not know how many zero groups each :: represented. Allowing :: only once ensures the expansion is unambiguous: the :: represents exactly as many 16-bit all-zero groups as needed to complete the address to eight groups total.
Question 4 True / False
IPv6 adoption has largely replaced IPv4, and NAT (Network Address Translation) is now obsolete for most modern networks as of 2026.
TTrue
FFalse
Answer: False
Despite decades of effort, IPv4 still dominates internet traffic as of 2026, and NAT remains widespread. While IPv6 deployment has grown substantially, the transition has been far slower than anticipated when IPv4 exhaustion was first projected. Many ISPs, home routers, and enterprise networks operate in dual-stack mode or still run IPv4-only. The predicted full obsolescence of NAT with IPv6 has not arrived — IPv4 addresses continue to circulate through trading markets, and IPv6 deployment remains uneven globally.
Question 5 Short Answer
Explain what SLAAC is, why it is a significant improvement over DHCPv4, and what mechanism IPv6 uses to verify that a self-configured address is actually unique.
Think about your answer, then reveal below.
Model answer: SLAAC (Stateless Address Autoconfiguration) lets an IPv6 host configure its own globally routable address without any server: it combines a network prefix from a Router Advertisement with a self-generated 64-bit interface ID. This is a significant improvement over DHCPv4, which requires a dedicated DHCP server to assign and track addresses, creating administrative overhead and a single point of failure. With SLAAC, adding a new host requires no server-side configuration at all. To verify uniqueness, the host performs Duplicate Address Detection (DAD) using Neighbor Discovery Protocol: it sends a Neighbor Solicitation message for its tentative address and listens for any response; if no other device claims the address, it proceeds to use it.
The stateless vs. stateful distinction is key: DHCPv4 requires a server to maintain state (a lease database of which address is assigned to which host). SLAAC distributes that responsibility — each host generates and verifies its own address, with DAD as the collision-avoidance mechanism. DHCPv6 still exists for scenarios requiring central control, but SLAAC is the default in most IPv6 networks.