nanog mailing list archives
Re: Broken PMTUD for . + TLD servers, was: Re: Smallest Transit MTU
From: Mark Andrews <Mark_Andrews () isc org>
Date: Mon, 10 Jan 2005 22:42:28 +1100
I receive DNS responses > 500 bytes every day (reported by PIX firewall). So it is an issue, no matter wgat is recomended in RFC.
And you most probable have EDNS clients (nameservers) inside your firewall making EDNS queries which return EDNS responses that are bigger than 512 bytes. EDNS has been standards track for over 5 years now. The majority of the nameservers in the world talk EDNS between themselves and have been for several years now. Only a few queries caused the EDNS response to exceed 512 bytes. With the introduction of the AAAA records for A.GTLD-SERVERS.NET and B.GTLD-SERVERS.NET any EDNS referral from the root servers for COM/NET now exceeds 512 bytes (520 minimum). A plain DNS referral to COM/NET is 509 bytes so any referal for an name longer than xx.com is dropping glue records for the COM/NET servers. The correct thing to do is to fix your firewall to handle the EDNS responses. Mark RFC 2671: Extension Mechanisms for DNS (EDNS0) -- Mark Andrews, ISC 1 Seymour St., Dundas Valley, NSW 2117, Australia PHONE: +61 2 9871 4742 INTERNET: Mark_Andrews () isc org
Current thread:
- Re: Smallest Transit MTU Sabri Berisha (Jan 05)
- Broken PMTUD for . + TLD servers, was: Re: Smallest Transit MTU Iljitsch van Beijnum (Jan 09)
- Re: Broken PMTUD for . + TLD servers, was: Re: Smallest Transit MTU Mark Andrews (Jan 09)
- Re: Broken PMTUD for . + TLD servers, was: Re: Smallest Transit MTU Iljitsch van Beijnum (Jan 09)
- Re: Broken PMTUD for . + TLD servers, was: Re: Smallest Transit MTU Alexei Roudnev (Jan 10)
- Re: Broken PMTUD for . + TLD servers, was: Re: Smallest Transit MTU Mark Andrews (Jan 10)
- Re: Broken PMTUD for . + TLD servers, was: Re: Smallest Transit MTU Suresh Ramasubramanian (Jan 10)
- Re: Broken PMTUD for . + TLD servers, was: Re: Smallest Transit MTU Mark Andrews (Jan 10)
- Re: Broken PMTUD for . + TLD servers, was: Re: Smallest Transit MTU Alexei Roudnev (Jan 10)
- Re: Broken PMTUD for . + TLD servers, was: Re: Smallest Transit MTU Mark Andrews (Jan 09)
- Broken PMTUD for . + TLD servers, was: Re: Smallest Transit MTU Iljitsch van Beijnum (Jan 09)