DHT versus DNS

Today was a great class discussion about Chord, DNS and co. Here is my list of questions and thoughts, I never got to ask in class, some got at least partially answered during the discussion.

Pro DHT:

• google does not use chord and uses more traditional hierarchical systems, but should we trust all of our data to single companies as hierarchical systems do?
• Authority: Can we trust the data if we replaced hierarchical DNS by Chord? Yes, if we have a hierarchical system of digital signatures (data and public keys signed by the root, country registrars and domain, subdomain owners), bootstrapped by root signatures which correspond to us needing to know the IP addresses of root servers.
• DHTs like chord do (theoretically) a beautiful job on load balancing and scalability (compare to BGP where each router needs the 200000 prefix entries routing information whereas chord only needs 31 fingers for 2^32 IDs)
  

Pro DNS:

• Malicious nodes can still spoof the non-existence of a certain domain in DHT.
  
• DHT provides no geographic locality, doesn't allow for techniques like anycast
• DNS recursers can be placed at strategic places, e.g. my provides can put a DNS recursers between its clients and and the DNS name servers, so DNS querries would follow how packets would flow instead of detouring which would mean latencies
• DNS has designated servers
• DNS caching is very efficient because 99% of all querries are probably for the same 1000 domains. This also plays to the importance of putting htem at good strategic places, i.e. each ISP should put it its own cache close to its edge routers