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UltraDNS vs. Deadwood

 

July 13 2013

UltraDNS sometimes adds upper-case letters to their replies. These host names were unable to resolve in Deadwood; I have updated Deadwood to have these names resolve.

==Deadwood update==

www.getcafecup.com did not resolve in Deadwood because UltraDNS, in their custom DNS server, decided to add upper-case in a reply from their server:

$ askmara Awww.getcafecup.com. 204.74.108.1
# Question: Awww.getcafecup.com.
WWW.getcafecup.com. +7200 a 216.242.93.163

Observe how the “www” becomes “WWW”. This is, as pointed out in the 0x20 hack document, unusual behavior. Not only does this break resolution in Deadwood (until today, anyway), it also results in bigger DNS packets (they do not compress quite as well).

To work around this behavior, I have had to patch Deadwood to ignore case when deciding whether a DNS label is the same.

It can be downloaded here:

http://www.maradns.org/deadwood/snap/
This is another out-of-band update. When Deadwood doesn’t resolve a domain on the Internet that other DNS servers can resolve, I usually patch Deadwood until it can resolve the name in question.

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