Posted on 10/30/2012 5:16:13 PM PDT by boop
I suspect that the problem is, packets are being truncated.
Could be happening at any of these:
1. at the firewall
2. within the server farm
3. because of some diagnostic procedures which have been set up to test for DNS query problems
In cases 1 and 2, it may be resolved by using an MTU of 1424 or 1492 but not “the standard” 1500. Some protocols don’t do well with the MTU set to 1500.
In case 3, port 53 and port 5353 may be subject to testing on both UDP and TCP protocols. It may help to stop that testing and only allow UDP.
Packet truncating -— probably because of MTU settings -— is possibly being solved for now, by allowing TCP for ports 53 and 5353?
When a repeat request is made because a packet was truncated, and the fallback is to TCP, it takes longer -— that is, UDP is faster than TCP.
A request via UDP is one packet. An answer via UDP is one packet.
A request via TCP involves a TCP handshake, a packet for the repeat request, a packet for the reply, and then a few packets of TCP that end the TCP connection.
That is, a UDP request and answer are 2 packets, but a TCP request and answer are 4+ packets.
If packets are being truncated, then there are many repeat requests, and if TCP is allowed for ports 53 and 5353, it takes much greater time.
I am wondering if, because of denial-of-service problems for FR, maybe John R. has set up DNS monitoring that is slowing things down because that monitoring of ports 53 and 5353 - using UDP and TCP - is complicating an existing packet truncation problem?
Something like that. I’m not an expert.
I really need to watch this movie again. My memory has not failed me completely as I can still hear Hal’s voice saying, “Dave”.
I guess we have different definitions of spurned. I didn’t receive Jim’s response of “thanks, but no thanks” as a scornful rejection. I know Jim appreciates that we want to help.
I should actually apologize to Jim, and I do, for putting him in an awkward position. I should have offered that help privately. My intentions were good. I wanted to ease some of the pressure on Jim and John. But with 20 years’ experience, I know the difficulties that outside help can create.
I can appreciate that this is what you do for a living, but if you’re not in a position to offer free help and Jim isn’t in a position to hire you anyway, then it’s moot.
I don’t know that we can say no progress is being made. Since John is the only person with access and he hasn’t posted to any of these threads, we don’t know what he’s figured out, tried, or even considered.
At the moment, around 4:45 AM EST Sunday, FR is very quick.
Well ... it was quick until I posted the previous reply, which hung a while; but it is faster in general, than it was yesterday (Saturday morning).
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