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Questions tagged [rfc]

A Request for Comments (RFC) is a publication of the Internet Engineering Task Force (IETF) and the Internet Society, the principal technical development and standards-setting bodies for the Internet.

A Request for Comments (RFC) is a publication of the Internet Engineering Task Force (IETF) and the Internet Society, the principal technical development and standards-setting bodies for the Internet.

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What's the maximum URL length in Tomcat?

And is it configurable? Can I set up Tomcat so that a URL with, say, 200K of query params goes through successfully to the contained servlet? Yes, I know one should use POST when you have lots of data; that's a less pleasant option in this…
Michael Gundlach
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DNS using CNAMEs breaks MX records?

We are trying to move all our websites we host to CNAMES as we are planning on moving servers in the new year and would like the ability to move some clients to one server and other clients somewhere else. We were planning on giving clients a unique…
johnwards
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Which RFCs should be cited as internet standards?

It's extremely common for RFCs to be cited in support of opinions (including Serverfault Q&A's), but the average IT employee has a very poor understanding in regards to which RFCs define standards and which ones are purely informative. This should…
Andrew B
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How does the DNS protocol switch from UDP to TCP?

Before anyone asks: I've seen When do DNS queries use TCP instead of UDP? and it doesn't answer my question. All I keep hearing is "if the answer is too long, DNS will use TCP". This does not explain how it happens though. So here's the situation:…
StanTastic
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SMTP allows for multiple FROM addresses in the RFC. Was this ever useful, why does this exist?

SMTP allows for multiple FROM addresses on the body (not the envelope) according to the RFCs. Has this feature ever been used for a legitimate purpose? Is it safe to discard messages that have multiple FROM addresses?
makerofthings7
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Legitimate reasons SMTP “MAIL FROM:” will not match “From:” Header in DATA

Is there ever a legitimate reason for the SMTP “MAIL FROM:” field to not match the “From:” field in the DATA section of a message, besides mailing lists? From…
dkovacevic
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Are two periods allowed in the local-part of an email address?

A third-party email gateway relay is refusing to process a message for an email address we're sending to. The address is in the format of firstname..lastname@recipientdomain.com (note the two periods). Is this allowed by RFC guidelines? RFC 2822…
Mike B
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Why is RFC 7505 (Null MX) necessary?

IETF RFC 7505 describes MX records for a domain/host that explicitly should not receive email. This is accomplished by pointing the MX at the Domain Name System root. For example, nomail.example.com. 86400 IN MX 0 "." Why is this needed? In my…
Alpha Whiskey
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RFC 1918 address on open internet?

In trying to diagnose a failover problem with my Cisco ASA 5520 firewalls, I ran a traceroute to www.btfl.com and, much to my surprise, some of the hops came back as RFC 1918 addresses. Just to be clear, this host is not behind my firewall and there…
longneck
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What's the point of repeating an email address in "The Envelope" and the "The Header"?

I learned that both the FROM address and the TO address is repeated in a hidden element called the "envelope", and then repeated again in the "body". Question Why isn't the envelope data copied into the "header"? Why does this duplication exist,…
TLDR
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Are one-letter host names valid?

RFC-952 (last sentence of point 1 under Assumptions) prohibits single-character host names and I have had experiences (over 7 years ago summer of 2002) where some services would refuse to work with single-character host names (because such names…
Isaac
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What is the point of the zones.rfc1918 file for Bind9?

Using an Ubuntu 10.04 LTS server in a standalone environment and trying to use views to serve two different subnets of clients. Getting errors regarding the zones.rfc1918 file, so I'd like to know what that file is used for. What's the point of…
romandas
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Where is the documentation that states TCP and UDP source port should be over 1024 and random?

I am having a hard time to find where it is documented that the source port should be random and in the range 1024-65535. In which RFC is this documented? Edit: First reference for privileged ports is in RFC2623 It seems that this is depending more…
Mircea Vutcovici
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RFC that requires DNS servers to respond to unknown domain requests

My domain registrar and DNS provide currently ignores DNS requests to unknown domains. By ignore I mean black-holes and never responds which causes my DNS clients and resolver libraries to retry, back off, and finally timeout. dig @NS3.DNSOWL.COM…
Gray
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Check public DNS health and RFC compliance

Every now and again I like to run checks on my DNS servers to make sure they are running right and to RFC spec. I used to use the DNSTools website to do this as it gave me a pretty good picture of what was going on - are all my servers responding to…
Zypher
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