Differences w/ PTR

Is the DNS name really belong to the node?
(Reverse record w/o forward zone admins' knowing)
Anyone can claim "www.ietf.org", same as PTR
Integrity between forward and reverse lookup
DNSSEC doesn't help, same as PTR
Malicious response injected from outsider
DNSSEC helps here, PTR has an advantage
With ICMPv6, we need PKI infrastructure + IPsec

Admin diffs
PTR: DNS zone admin needs to configure single DNS server
ICMPv6: every node has to be configured with a DNS name