This chapter covers IPv6 connectivity troubleshooting, a critical skill for the N10-009 exam. IPv6 is now a required part of the CompTIA Network+ objectives, and troubleshooting IPv6 connectivity issues appears in approximately 10–15% of exam questions. You will learn the common causes of IPv6 connectivity failures, the tools and commands used to diagnose them, and the step-by-step process to isolate and resolve problems. Mastery of IPv6 troubleshooting is essential for any network professional, as IPv6 deployment continues to grow globally.
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Imagine a city where every building has a unique GPS coordinate (latitude/longitude) instead of a street address. The postal system uses these coordinates to deliver mail directly. There is no need for a central directory or address translation because every location is globally unique. When a letter is sent, the sender writes the recipient's full GPS coordinates on the envelope. The postal service uses a hierarchical routing system: first, it sorts by continent (the first few digits of the coordinates), then by country, region, city, and finally the exact building. This hierarchy allows efficient routing without needing to know every address individually. If a building moves (changes its network), it gets a new coordinate, but the postal system adapts because the coordinates are self-describing. In IPv6, each interface has a globally unique 128-bit address, eliminating the need for NAT (like a central directory). The hierarchical addressing (global prefix, subnet ID, interface ID) enables efficient routing aggregation, similar to how the postal system sorts by regions. Just as a GPS coordinate contains all the information needed to locate a building, an IPv6 address contains all the information needed to route a packet to its destination anywhere in the world.
What is IPv6 Connectivity Troubleshooting?
IPv6 connectivity troubleshooting involves identifying and resolving issues that prevent IPv6-enabled devices from communicating over an IPv6 network. Unlike IPv4, IPv6 eliminates the need for Network Address Translation (NAT) by providing a vast address space, but it introduces new complexities such as multiple address types (link-local, unique local, global unicast), neighbor discovery, and stateless address autoconfiguration (SLAAC). Troubleshooting IPv6 requires understanding these mechanisms and using appropriate tools like ping6, traceroute6, ipconfig/ifconfig, and protocol analyzers.
Why IPv6 Troubleshooting Matters for N10-009
The CompTIA Network+ N10-009 exam includes IPv6 troubleshooting under Objective 5.3: "Given a scenario, troubleshoot common network connectivity issues." You must be able to identify symptoms of IPv6 problems, use the correct diagnostic commands, and interpret the output to isolate faults. Common issues include incorrect address configuration, router advertisement problems, duplicate address detection failures, and routing issues. The exam will present scenarios where you must choose the correct troubleshooting step or tool.
How IPv6 Addressing Works – A Brief Review
IPv6 addresses are 128 bits, typically written as eight groups of four hexadecimal digits (e.g., 2001:db8::1). Key address types:
Link-local addresses (fe80::/10): Used for communication within a single network segment. Every IPv6 interface automatically generates a link-local address. Routers do not forward packets with link-local source or destination addresses.
Unique local addresses (fc00::/7): Similar to IPv4 private addresses (RFC 4193). Used for internal communication within a site. Not routable on the global internet.
Global unicast addresses (2000::/3): Globally routable addresses, equivalent to IPv4 public addresses. They consist of a global routing prefix (usually /48 or /32), a subnet ID (usually /64), and an interface ID (64 bits).
Multicast addresses (ff00::/8): Used for one-to-many communication. All IPv6 nodes listen to the all-nodes multicast address ff02::1.
Anycast addresses: From the same address space as unicast, but multiple interfaces share the same address; packets are delivered to the nearest interface (by routing distance).
Common IPv6 Connectivity Issues
#### 1. Incorrect Address Configuration
Devices may have manually configured static IPv6 addresses, or they may obtain addresses via SLAAC or DHCPv6. Common misconfigurations:
Wrong prefix length: Most IPv6 subnets use a /64 prefix. Using a different prefix length (e.g., /48 or /56) on a LAN can break neighbor discovery because SLAAC and DHCPv6 expect a /64.
Duplicate addresses: IPv6 uses Duplicate Address Detection (DAD) to ensure no two interfaces on the same link share the same address. If DAD detects a duplicate, the address is not assigned. This can happen if a static address conflicts with an autoconfigured address.
Misconfigured gateway: The default gateway must be a router's link-local address, not the global address, because the default route is to the router's link-local address on the same link.
#### 2. Router Advertisement (RA) Problems
Routers send Router Advertisement (RA) messages periodically (default every 200 seconds) or in response to Router Solicitations from hosts. RAs contain:
Prefix information: The network prefix (e.g., 2001:db8:1::/64) and its lifetime.
Flags: Managed (M) flag indicates DHCPv6 is available; Other (O) flag indicates DHCPv6 can provide other configuration (like DNS).
Default router information: The router's link-local address and its lifetime.
Common RA issues:
No RA received: If a host does not receive an RA, it cannot configure a global address or default gateway (unless using DHCPv6 with M flag). Causes: router not configured to send RAs, firewall blocking ICMPv6 type 134, or VLAN mismatch.
Incorrect prefix: If the RA advertises a wrong prefix, hosts will configure addresses that don't match the subnet, causing unreachability.
Short lifetimes: If the prefix or router lifetime is too short, hosts may expire their addresses and lose connectivity.
#### 3. Neighbor Discovery (ND) Failures
IPv6 uses Neighbor Discovery Protocol (NDP) for address resolution (replacing ARP) and neighbor reachability detection. NDP uses ICMPv6 messages:
Neighbor Solicitation (NS): ICMPv6 type 135, sent to resolve a neighbor's link-layer address or to perform DAD.
Neighbor Advertisement (NA): ICMPv6 type 136, sent in response to an NS.
Router Solicitation (RS): ICMPv6 type 133, sent by hosts to request an RA.
Router Advertisement (RA): ICMPv6 type 134, sent by routers.
Redirect: ICMPv6 type 137, used to inform a host of a better next-hop.
Common ND issues:
Duplicate Address Detection (DAD) failures: If a host sends an NS for its tentative address and receives a NA (or another NS with the same target), DAD fails. This can happen if two hosts are configured with the same static address or if a host is configured with the same address as the router's interface.
Neighbor cache corruption: The neighbor cache (similar to ARP cache) can become stale or poisoned. Use netsh interface ipv6 show neighbors (Windows) or ip -6 neigh show (Linux) to inspect.
Missing neighbor entries: If a host cannot resolve a neighbor's link-layer address, it cannot communicate. Check for firewall rules blocking ICMPv6.
#### 4. Routing Issues
IPv6 routing issues are similar to IPv4: incorrect static routes, missing routes, or routing protocol problems. Common IPv6-specific routing issues:
Missing default route: The default route in IPv6 is ::/0 pointing to the next-hop router's link-local address. If the default route is missing or points to an unreachable next-hop, hosts cannot reach external networks.
Route summarization errors: Incorrect route aggregation can cause black holes. For example, summarizing 2001:db8:1::/48 and 2001:db8:2::/48 into 2001:db8::/48 may include unintended subnets.
Routing protocol misconfiguration: OSPFv3 (for IPv6) uses different configuration than OSPFv2. Ensure router IDs are set correctly and interfaces are enabled for OSPFv3.
#### 5. Firewall and Security Issues
IPv6 traffic can be blocked by firewalls or Access Control Lists (ACLs). Common issues:
ICMPv6 filtering: ICMPv6 is essential for NDP and path MTU discovery. Blocking ICMPv6 can break connectivity. For example, blocking ICMPv6 type 2 (Packet Too Big) prevents path MTU discovery, leading to packet drops.
Inbound filtering: Firewalls may block incoming IPv6 traffic that is necessary for certain applications.
IPv6 ACLs on routers: Misconfigured ACLs can permit or deny IPv6 traffic incorrectly. Use show ipv6 access-list (Cisco) to verify.
#### 6. DNS Resolution Issues
IPv6 hosts may have both A (IPv4) and AAAA (IPv6) DNS records. Common issues:
Missing AAAA records: If a server has an IPv6 address but no AAAA record, clients cannot reach it via IPv6.
DNS server not reachable over IPv6: If the DNS server is only reachable via IPv4, but the client prefers IPv6, resolution may fail.
DNS64: In NAT64 environments, DNS64 synthesizes AAAA records from A records. Misconfiguration can cause resolution failures.
Troubleshooting Tools and Commands
#### ping6 (or ping -6)
Tests basic IPv6 connectivity. Example:
ping6 2001:db8::1If ping fails, the issue could be local (address configuration, neighbor discovery) or remote (routing, firewall).
#### traceroute6 (or tracert -6 on Windows)
Traces the path to a destination. Example:
traceroute6 2001:db8::1Useful for identifying where packets are dropped.
#### ipconfig (Windows) / ifconfig (Linux) / ip addr show
Displays IPv6 addresses and configuration. On Windows:
ipconfig /allLook for IPv6 Address, Link-local IPv6 Address, Default Gateway (IPv6).
#### netsh (Windows)
Advanced IPv6 configuration and diagnostics:
netsh interface ipv6 show addresses
netsh interface ipv6 show neighbors
netsh interface ipv6 show route
netsh interface ipv6 show destinationcache#### ip (Linux)
Modern Linux tool for IPv6:
ip -6 addr show
ip -6 neigh show
ip -6 route show#### tcpdump / Wireshark
Packet capture to analyze ICMPv6 messages. Example:
tcpdump -i eth0 icmp6Look for RAs, NS/NA, DAD messages.
Step-by-Step Troubleshooting Methodology
Verify IPv6 address assignment: Use ipconfig or ip addr to check if the interface has a link-local address (fe80::/10) and a global/unique local address. If no link-local address, the interface is not IPv6-enabled.
Check default gateway: Ensure the default route exists and points to a reachable next-hop. On Windows: netsh interface ipv6 show route; on Linux: ip -6 route show default.
Test link-local connectivity: Ping the router's link-local address from the host. If this fails, the issue is on the local link (cabling, switch, VLAN, or firewall).
Test global connectivity: Ping the destination's global address. If fails, use traceroute to identify where packets stop.
Verify DNS resolution: Use nslookup or dig to check for AAAA records. Example: nslookup -type=AAAA example.com.
Check firewall rules: Temporarily disable firewalls to see if they are blocking traffic. Review ACLs on routers.
Capture packets: Use Wireshark to capture ICMPv6 traffic. Look for RAs, DAD messages, and NS/NA exchanges.
Interaction with Related Technologies
DHCPv6: Works alongside SLAAC. The M flag in RAs indicates DHCPv6 is used for address assignment; the O flag indicates DHCPv6 is used for other configuration (DNS, domain). Troubleshooting DHCPv6 involves checking DHCPv6 server reachability, scope configuration, and relay agents.
NAT64: Translates IPv6 to IPv4 for accessing IPv4-only resources. Issues include incorrect prefix (usually 64:ff9b::/96) and DNS64 misconfiguration.
Dual Stack: Both IPv4 and IPv6 run simultaneously. Troubleshooting may involve determining which stack is failing. Use ping (IPv4) and ping6 (IPv6) to isolate.
Tunneling: 6to4, Teredo, ISATAP. These transition technologies encapsulate IPv6 in IPv4. Troubleshooting involves checking tunnel endpoints, MTU issues, and firewall rules that may block protocol 41 (for 6to4).
Verify IPv6 Address Assignment
Check if the interface has a valid IPv6 address. Use `ipconfig /all` on Windows or `ip -6 addr show` on Linux. Look for a link-local address (fe80::/10) — every IPv6 interface must have one. If missing, IPv6 is disabled or the interface is down. Also check for a global unicast or unique local address. If the host is supposed to use SLAAC, verify that it has received a Router Advertisement (RA). If using DHCPv6, check that the DHCPv6 client has obtained an address. A common misconfiguration is a missing or incorrect prefix length (should be /64 for SLAAC).
Check Default Gateway
Verify that the host has a default route. On Windows: `netsh interface ipv6 show route` and look for a route with `::/0` and a next-hop link-local address. On Linux: `ip -6 route show default`. The default gateway should be the router's link-local address, not a global address. If the default route is missing, the host cannot reach external networks. Possible causes: no RA received, RA does not set the router flag, or the router lifetime expired. Manually add a default route if needed, but first investigate why RA is missing.
Test Link-Local Connectivity
Ping the router's link-local address from the host. Use `ping6 fe80::...` (include the zone ID on Windows: `ping fe80::...%<interface index>`). On Linux, use `ping6 -I eth0 fe80::...`. If this ping fails, the problem is on the local link. Check physical connectivity, VLAN membership, switch port configuration, and firewall rules. Also verify that the router is actually sending RAs (use packet capture). If link-local ping succeeds, the Layer 2 and basic IPv6 neighbor discovery are working.
Test Global Connectivity
Ping a known global IPv6 address (e.g., 2001:4860:4860::8888 for Google DNS). If this fails but link-local ping succeeded, the issue is beyond the local link. Use `traceroute6` to see where packets stop. Common causes: missing default route (already checked), incorrect static route on the router, routing protocol issues, or firewall blocking ICMPv6 or the destination port. Also check if the destination is reachable via IPv4 (dual stack) to confirm the problem is IPv6-specific.
Verify DNS Resolution
Check if the host can resolve IPv6 addresses. Use `nslookup -type=AAAA example.com` or `dig AAAA example.com`. If no AAAA records are returned, the server may not have IPv6 DNS entries. If the DNS server itself is not reachable over IPv6, resolution may fail. Check the DNS server addresses configured on the host (from RA or DHCPv6). Use `netsh interface ipv6 show dnsservers` (Windows) or `cat /etc/resolv.conf` (Linux). If DNS fails, the host may fall back to IPv4, but applications may prefer IPv6 and fail.
Capture ICMPv6 Traffic
Use Wireshark or tcpdump to capture ICMPv6 packets on the host's interface. Filter for `icmp6`. Look for Router Advertisements (type 134) to confirm the router is sending them. Check for Neighbor Solicitations (type 135) and Advertisements (type 136) to see if address resolution is working. Duplicate Address Detection (DAD) sends NS with source address :: (unspecified). If you see NS messages for the host's address with no NA response, DAD may be failing. Also look for ICMPv6 errors (type 1) like Destination Unreachable.
Enterprise Scenario 1: Dual-Stack Migration at a University
A university is migrating its campus network from IPv4-only to dual-stack. The IT team configures routers to send RAs with the correct /64 prefix and enables DHCPv6 for DNS and other options. After deployment, some users report they cannot reach external IPv6 websites. Troubleshooting reveals that the default gateway on some subnets points to an old router that does not have IPv6 routing enabled. The fix: ensure all routers have IPv6 routing enabled (ipv6 unicast-routing on Cisco) and that the default route is redistributed via the routing protocol (OSPFv3). Additionally, some firewalls were blocking ICMPv6 type 2 (Packet Too Big), causing path MTU discovery failures. The team updated firewall rules to allow essential ICMPv6 types.
Enterprise Scenario 2: SLAAC vs. DHCPv6 at a Large Corporation
A corporation uses SLAAC for address assignment but needs to provide DNS server addresses. They set the O flag in RAs to indicate DHCPv6 for other configuration. However, some hosts (especially older Windows versions) do not support DHCPv6 for DNS and rely on RDNSS (Recursive DNS Server option) in RAs. The network team initially did not configure RDNSS, so hosts had no DNS servers and could not resolve names. The solution: configure both RDNSS in RAs and DHCPv6 for redundancy. The team also discovered that some routers were not sending RAs due to an ACL blocking ICMPv6 type 134. After correcting the ACL, hosts received RAs and configured addresses correctly.
Enterprise Scenario 3: IPv6-Only Data Center with NAT64/DNS64
A cloud provider deploys an IPv6-only data center but must allow access to IPv4-only external services. They implement NAT64 with the well-known prefix 64:ff9b::/96 and DNS64 to synthesize AAAA records. A customer reports that their application cannot connect to an external API. Troubleshooting reveals that the DNS64 server is not synthesizing records for that domain because the domain's A record has a TTL of 0, causing the DNS64 to skip synthesis. The fix: adjust DNS64 configuration to handle zero-TTL records. Also, the NAT64 gateway was dropping packets due to an MTU issue: the IPv6 path MTU was 1500, but the IPv4 path MTU was 1400, causing fragmentation. The team configured the NAT64 gateway to perform fragmentation and set the DF bit appropriately.
N10-009 Exam Focus: IPv6 Connectivity Troubleshooting (Objective 5.3)
The CompTIA Network+ N10-009 exam tests your ability to troubleshoot IPv6 connectivity issues in scenario-based questions. You must be able to interpret symptoms, choose the correct diagnostic tool, and identify the root cause. Key objective codes: 5.3 (Troubleshoot common network connectivity issues).
Common Wrong Answers and Why Candidates Choose Them
"The host has no IPv6 address because DHCPv6 is not configured." Candidates often assume DHCPv6 is required for address assignment. In reality, SLAAC can assign addresses without DHCPv6. The correct answer often involves checking for Router Advertisements.
"The default gateway should be the router's global unicast address." Many candidates think the default gateway is a global address. In IPv6, the default gateway is the router's link-local address. Pinging the global address may work, but the default route uses the link-local address.
"IPv6 does not need ARP, so neighbor discovery is not required." While IPv6 uses NDP instead of ARP, NDP is essential. Some candidates think NDP is optional. In fact, without NDP, hosts cannot resolve link-layer addresses.
"Blocking all ICMPv6 is safe because it is not needed for IPv6." ICMPv6 is critical for NDP, path MTU discovery, and error reporting. Blocking it can break IPv6. The exam may present a scenario where a firewall blocks ICMPv6 and connectivity fails.
Specific Numbers and Terms to Memorize
Prefix length for SLAAC: /64. Using a different prefix can break SLAAC.
Router Advertisement interval: Default every 200 seconds (RFC 4861).
Router lifetime: Default 1800 seconds (30 minutes) in RAs.
Duplicate Address Detection (DAD): Uses NS with source address :: (unspecified) and destination ff02::1 (all-nodes multicast).
ICMPv6 types: RS (133), RA (134), NS (135), NA (136), Redirect (137).
Well-known NAT64 prefix: 64:ff9b::/96.
Link-local prefix: fe80::/10.
Multicast addresses: ff02::1 (all nodes), ff02::2 (all routers).
Edge Cases the Exam Loves
Host configured with static IPv6 address but no default route: The host can communicate on the local link but not beyond.
Router sends RA with M flag set, but no DHCPv6 server exists: Hosts will try DHCPv6 and fail, then may fall back to SLAAC if configured.
Duplicate address detected via DAD: The host will not use that address, and you must resolve the conflict.
IPv6 tunnel (e.g., 6to4) misconfiguration: The tunnel endpoint may be unreachable, or the relay router may not be configured.
How to Eliminate Wrong Answers
If the question mentions "cannot reach external networks but can ping local hosts," the issue is likely routing (default gateway or missing route).
If the question says "host has a link-local address but no global address," suspect missing RAs or wrong prefix.
If the question involves "firewall blocking ICMP," look for answers that mention allowing ICMPv6 types 133-137.
Always check the default gateway: it must be a link-local address.
Every IPv6 interface must have a link-local address (fe80::/10) for neighbor discovery and default gateway communication.
Default gateway in IPv6 is always the router's link-local address, not a global address.
Router Advertisements (RAs) are sent every 200 seconds by default (RFC 4861) and contain prefix and configuration flags.
Duplicate Address Detection (DAD) uses Neighbor Solicitation messages with source address :: (unspecified).
ICMPv6 types 133-137 are essential for NDP; blocking them breaks IPv6 connectivity.
SLAAC assigns addresses using /64 prefix; DHCPv6 is optional and often used for additional configuration.
Common troubleshooting commands: ping6, traceroute6, ipconfig, netsh, ip -6, tcpdump.
NAT64 uses prefix 64:ff9b::/96 to translate IPv6 to IPv4.
Dual-stack hosts prefer IPv6 over IPv4 by default (RFC 6724).
Missing AAAA DNS records cause IPv6 connectivity failures even if IPv6 is configured.
These come up on the exam all the time. Here's how to tell them apart.
SLAAC (Stateless Address Autoconfiguration)
No server required; hosts derive addresses from RAs.
Uses /64 prefix from RA and EUI-64 or random interface ID.
Cannot provide DNS server addresses unless RDNSS is used.
Less control over address assignment (no logging).
Suitable for simple networks with no need for address tracking.
DHCPv6 (Stateful)
Requires a DHCPv6 server (can be stateful or stateless).
Provides exact address assignment with lease times.
Can provide DNS server addresses, domain names, and other options.
Offers centralized control and logging of address assignments.
Suitable for enterprise networks requiring audit trails and policy.
Mistake
IPv6 addresses are always globally unique, so no two devices can have the same address.
Correct
IPv6 addresses can be duplicated if misconfigured. Duplicate Address Detection (DAD) prevents address conflicts, but if DAD fails or is disabled, duplicates can occur. Also, unique local addresses (fc00::/7) can be reused across different sites.
Mistake
IPv6 does not need a default gateway because every address is globally routable.
Correct
IPv6 still requires a default gateway to reach networks outside the local link. The default gateway is the router's link-local address. Without it, hosts cannot communicate off-link.
Mistake
DHCPv6 is required for IPv6 address assignment.
Correct
SLAAC (Stateless Address Autoconfiguration) can assign addresses without DHCPv6. DHCPv6 is optional and often used for additional configuration (DNS, domain). The M flag in RAs indicates DHCPv6 is used for addresses.
Mistake
ICMPv6 is not essential for IPv6 and can be safely blocked.
Correct
ICMPv6 is critical for Neighbor Discovery, Path MTU Discovery, and error reporting. Blocking ICMPv6 can break IPv6 connectivity. Specifically, block only unnecessary types, not all ICMPv6.
Mistake
IPv6 troubleshooting is the same as IPv4 troubleshooting.
Correct
While similar, IPv6 introduces new protocols (NDP, SLAAC, DHCPv6) and address types. Tools and commands differ (e.g., ping6, traceroute6). Understanding these differences is essential for accurate troubleshooting.
Reveal each answer, then mark whether you got it right. Score 60%+ to unlock the next chapter.
First, verify that the router is sending Router Advertisements (RAs). Use a packet capture (tcpdump or Wireshark) to check for ICMPv6 type 134 messages. If no RAs are received, ensure the router interface is enabled for IPv6 and that `ipv6 unicast-routing` is enabled (Cisco). Also check for ACLs blocking ICMPv6. If RAs are sent, verify that the host is configured to accept them (SLAAC enabled). On Windows, check the 'Automatic' setting for IPv6. Also ensure the prefix length in the RA is /64; other lengths may cause SLAAC to fail.
SLAAC (Stateless Address Autoconfiguration) allows hosts to generate their own IPv6 address using the prefix from Router Advertisements and a self-generated interface ID (EUI-64 or random). It does not require a server. DHCPv6 (Stateful) assigns addresses from a server, similar to DHCP for IPv4, and can provide additional configuration like DNS servers. DHCPv6 can also be stateless (only providing configuration, not addresses) when used with SLAAC. The M flag in RAs indicates whether DHCPv6 is used for addresses.
Use the command `netsh interface ipv6 show neighbors` in an elevated Command Prompt. This displays the neighbor cache, including IPv6 addresses and their corresponding link-layer (MAC) addresses. The state column shows if the entry is reachable, stale, or incomplete. A missing entry for a neighbor indicates that address resolution failed. You can also use `arp -a` but that shows IPv4 ARP cache only.
This indicates an IPv6-specific issue. Common causes: the destination does not have an IPv6 address (no AAAA record), a firewall is blocking ICMPv6, the default gateway is missing or incorrect, or there is a routing problem for IPv6. Use `traceroute6` to see where packets stop. Also verify that the host has a valid IPv6 address and default route. If the destination is reachable via IPv4, the problem is likely with the IPv6 path.
DAD is a mechanism in IPv6 Neighbor Discovery that ensures no two interfaces on the same link use the same unicast address. When an interface is assigned a new address (e.g., via SLAAC or static config), it sends a Neighbor Solicitation (NS) with the target address set to the new address and the source address set to the unspecified address (::). If no Neighbor Advertisement (NA) is received in response (and no other NS with the same target), the address is considered unique. If a response is received, the address is marked as duplicate and not assigned.
Use the `ipv6 route` command. The syntax is: `ipv6 route <prefix/prefix-length> <next-hop-address>`. The next-hop address is typically the link-local address of the neighboring router. For example: `ipv6 route 2001:db8:1::/64 fe80::1`. You must also specify the exit interface if the next-hop is link-local: `ipv6 route 2001:db8:1::/64 gigabitethernet0/0 fe80::1`. To verify, use `show ipv6 route`.
The well-known NAT64 prefix is 64:ff9b::/96, as defined in RFC 6052. This prefix is used to synthesize IPv6 addresses from IPv4 addresses for translation. For example, the IPv4 address 192.0.2.1 would be mapped to 64:ff9b::c000:201. NAT64 gateways use this prefix to route traffic from IPv6-only hosts to IPv4 destinations. Some deployments use custom prefixes instead.
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