pix6.3 fixip dns

Oct 12, 2006 1 Replies

hi, just came accross a config: fixup protocol dns maximum-length 2048


the customer has problems resolving names, some sites are not resolved at all, others slow, others ok.



I suspect it's a problem in their internal DNS, I was just wondering why someone would set this so high (default is 512) or if this could be related.


thanks, M



Modify it to 4096.

EDNS0 allows the resolver to enlarge the UDP packetsize for DNS to up to

40ß96 bytes.

This is useful to gather information which is significantly larger then 512 bytes, i.e. DNSSec. Especially the reverse lookup zones *.in-addr.arpa are signed. Other sources of larger packets are SFP or Domainkey records. So you might run into this problem easily.

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