"A" record gets deleted when "AAAA" record gets registered

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Symptoms

Client deletes its A record when the client dynamically updates the AAAA record that also includes an A record update with TTL=0, this happens if DHCP option 81 set by DHCP server.

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Cause

By design, either the DNS client or the DHCP Server (Option 81), must perform the dynamic update. The DNS client and the DHCP Server updating the DNS record can be called update mixed mode of operation. Update mixed mode of operation is not supported.

Sequence of events
1) The DHCP server (Option 81 is configured) registers the IPv4 records for the client machine

2) When 6to4 is enabled, then the DNS client registers the AAAA record on the DNS server, however; before the DNS client registers the AAAA record, stale records need to be considered, so the DNS Client sends IPv6 as well as well as a IPv4 record with a Time To Live (TTL) equal to 0.

When the IPv4 A record is registered with a TTL = 0, the TTL = 0 indicates to delete the A record.

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