Skip to content

Cannot handle MTU-reklated timeouts?

From one vantage point, Knot resolver cannot get answers with DNS+DNSSEC, from any of the name servers. It cannot retry without EDNS because it would break DNSSEC but shouldn't it retry automatically with TCP?

% dig A www.afnic.fr

; <<>> DiG 9.11.2-P1-1-Debian <<>> A www.afnic.fr
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: SERVFAIL, id: 6594
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags: do; udp: 4096
;; QUESTION SECTION:
;www.afnic.fr.		IN A

;; Query time: 2066 msec
;; SERVER: 192.168.2.254#53(192.168.2.254)
;; WHEN: Thu Jan 25 15:44:33 UTC 2018
;; MSG SIZE  rcvd: 41
 
% dig @ns2.nic.fr A www.afnic.fr          

; <<>> DiG 9.11.2-P1-1-Debian <<>> @ns2.nic.fr A www.afnic.fr
; (2 servers found)
;; global options: +cmd
;; connection timed out; no servers could be reached

% dig +nodnssec @ns2.nic.fr A www.afnic.fr

; <<>> DiG 9.11.2-P1-1-Debian <<>> +nodnssec @ns2.nic.fr A www.afnic.fr
; (2 servers found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 3789
;; flags: qr aa rd; QUERY: 1, ANSWER: 3, AUTHORITY: 5, ADDITIONAL: 10
;; WARNING: recursion requested but not available

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
; COOKIE: 4bbe8d53108364eabca57f7a5a69fbee7ec3de6b2d63de14 (good)
;; QUESTION SECTION:
;www.afnic.fr.		IN A

;; ANSWER SECTION:
www.afnic.fr.		600 IN CNAME www.nic.fr.
www.nic.fr.		600 IN CNAME lb01-1.nic.fr.
lb01-1.nic.fr.		600 IN A 192.134.5.24

;; AUTHORITY SECTION:
nic.fr.			172800 IN NS ns2.nic.fr.
nic.fr.			172800 IN NS ns1.nic.fr.
nic.fr.			172800 IN NS ns3.nic.fr.
nic.fr.			172800 IN NS ns6.ext.nic.fr.
nic.fr.			172800 IN NS ns1.ext.nic.fr.

;; ADDITIONAL SECTION:
ns1.nic.fr.		172800 IN AAAA 2001:67c:2218:2::4:1
ns2.nic.fr.		172800 IN AAAA 2001:660:3005:1::1:2
ns3.nic.fr.		172800 IN AAAA 2001:660:3006:1::1:1
ns6.ext.nic.fr.		172800 IN AAAA 2001:620:0:ff::2f
ns1.ext.nic.fr.		172800 IN A 193.51.208.13
ns1.nic.fr.		172800 IN A 192.134.4.1
ns2.nic.fr.		172800 IN A 192.93.0.4
ns3.nic.fr.		172800 IN A 192.134.0.49
ns6.ext.nic.fr.		172800 IN A 130.59.31.29

;; Query time: 7 msec
;; SERVER: 2001:660:3005:1::1:2#53(2001:660:3005:1::1:2)
;; WHEN: Thu Jan 25 15:46:54 UTC 2018
;; MSG SIZE  rcvd: 414

% dig +tcp @ns2.nic.fr A www.afnic.fr

; <<>> DiG 9.11.2-P1-1-Debian <<>> +tcp @ns2.nic.fr A www.afnic.fr
; (2 servers found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 25722
;; flags: qr aa rd; QUERY: 1, ANSWER: 6, AUTHORITY: 6, ADDITIONAL: 19
;; WARNING: recursion requested but not available

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags: do; udp: 4096
; COOKIE: 55f9b6f5342698c35f05f3875a69fbfc73e77c5cf608ac42 (good)
;; QUESTION SECTION:
;www.afnic.fr.		IN A

;; ANSWER SECTION:
www.afnic.fr.		600 IN CNAME www.nic.fr.
www.afnic.fr.		600 IN RRSIG CNAME 8 3 600 (
				20180213225107 20180115074143 64491 afnic.fr.
				OrzJ7+UmRiFpyz33DA7VvL7ZQADDd862bR6PSWrCuSIv
				U4eE6BHKDjXkzDpp2TYUI+n+NSmkkOkmsD4tlOhfo8ao
				573RhBnmoPVO3dnqrUWZf8omi4KfpS9sZmybV30DzN8m
				lB2UbO5FtvN5p3L8kVWmqcxZyW/fNO07IUf7bwoIAoaS
				XzJQfAPfoa7i93kbfleI5OTpjwmfHHEdcnl+a6bpcv2i
				Uquo34c5SfD3aWThw54mS+zQXEhaW38Oxbnfsz0tSy4V
				0ng4o4PVFqF/wpWt1x1NxfCe6wg6ODFhutuzDu7EQdH0
				OI6Btn9lsMEl5hNEJGksudyjlvV9SkYyug== )
www.nic.fr.		600 IN CNAME lb01-1.nic.fr.
www.nic.fr.		600 IN RRSIG CNAME 8 3 600 (
				20180222212642 20180123144323 64491 nic.fr.
				TUVAhMpnA+WtxiisXpBtVf+MkkwLm1vApGmzy23lc9+m
				/Mi6yBuiRaXVuWUZ/M8CoOzm8vL7maU4hI5tgqwccMem
				nAnrgM34m93rKf5AUnYLw85OHPgf7d6Kr79O6UOI5tUX
				R5l4pyZv3HpYPNsOmSUxkXYURZrByuF6IvXV2J+yzvDV
				k28e5mTAMc2sTrDZJ/7ZGF6vi6FoGp/Qe/gujPv3GBLw
				CMCNd9FXYyLP8I22iLoPPxcgOhulUBNHuzGjM3X4GIAm
				9D3Jjz/Hrm2G6mFgcsyt0CUOSK+ClZx4temUrEI73KPK
				I6VWzvgLVV2pzdpDDNaZUJHnDY0ovfxtgg== )
lb01-1.nic.fr.		600 IN A 192.134.5.24
lb01-1.nic.fr.		600 IN RRSIG A 8 3 600 (
				20180220192248 20180122044323 64491 nic.fr.
				JoKmE6E79tkrh4elgng92IJ4lErXM1yMX8pu6jsh/6Gc
				hrY6KsCh9YLAab4qKqDGOEjoqH74op3HWw0GY3usAjPN
				k4+FtZoGfZGLLfREOn0oZSgSSHjiga+VcnVFS7Fw2v8s
				WI+TzCsOYRyDOtUSMielnanfdxvi4HtNieh0u9m+tz5G
				BwVsQAdMD3o34P48DBZASjXCNvcoMpTCI5E0r6wXhnqI
				vNAAW2JS1pHLXUxxqme22p/g8HWcZ+cW4uLTBAlZW8Xe
				6uLQYMircoT7EhPOndQMrzHB0rqjrHYdXyJe/htJEcfP
				XR5sQqOGQFMuTiPXXv1uP0v0wme1161kkA== )

;; AUTHORITY SECTION:
nic.fr.			172800 IN NS ns3.nic.fr.
nic.fr.			172800 IN NS ns2.nic.fr.
nic.fr.			172800 IN NS ns1.ext.nic.fr.
nic.fr.			172800 IN NS ns6.ext.nic.fr.
nic.fr.			172800 IN NS ns1.nic.fr.
nic.fr.			172800 IN RRSIG	NS 8 2 172800 (
				20180210074028 20180111115419 64491 nic.fr.
				EcoBebipzdTzUEP8TGx5m72+NlQV7a57S9aXZyYLxmiI
				1n8w23ScIWE5w5aBUwZdlg9wDvkBSRX17VUxG37wxEgR
				VxD+qH0vLIl45GjRUSaWbWXPLjWTuAoy+5euDKsdT/Ej
				x1wOu0KcUPxKBur6eTEj0TaNETSD7h4b5eTouff/JoWV
				T727DCkr9lYSMqrC7jFav6YiJRlv7zXMWRFMPlD4hssC
				ejLQ2E3OlPE+0SoqpIVJI0TqzNJYEiPnSJ7AaDuI2dji
				fT6E4iArnU8XSRtXjMrtBJd6oRNJn+v9qH73oIiMpZC1
				5AEbfH1q9tj8MT1FCa43iEePOr36+WFUbg== )

;; ADDITIONAL SECTION:
ns1.nic.fr.		172800 IN AAAA 2001:67c:2218:2::4:1
ns2.nic.fr.		172800 IN AAAA 2001:660:3005:1::1:2
ns3.nic.fr.		172800 IN AAAA 2001:660:3006:1::1:1
ns6.ext.nic.fr.		172800 IN AAAA 2001:620:0:ff::2f
ns1.ext.nic.fr.		172800 IN A 193.51.208.13
ns1.nic.fr.		172800 IN A 192.134.4.1
ns2.nic.fr.		172800 IN A 192.93.0.4
ns3.nic.fr.		172800 IN A 192.134.0.49
ns6.ext.nic.fr.		172800 IN A 130.59.31.29
ns1.ext.nic.fr.		172800 IN RRSIG	A 8 4 172800 (
				20180218001157 20180119024323 64491 nic.fr.
				EbvmCLKgiLEojrvu+G9jNIWtAX0zuu/7NOpU1Tisjpop
				Zx9hX7qYb1HLCH1qhU8s3iBhFedqSUXF6rtZHzz2qtJ+
				h+G4UgNAWCyDsHVeH5lisXirUDx+Hp9+Z1EAoUb5Kf6F
				0f2tNAt6MkJYBg+DjxcuRDRWoG5LBBphPz8mhgnoVp9r
				Jh4C6XqfrT9T18k999ijdIcIfXwhP+ghmXhg0zW2PIUr
				3B9KKkfo4YDWJOZ2hpH3wM8l0Ka/C6v9naU1RQ+j01Ay
				izENN2xnevbaTCp4D6FYE2JVWHASuYlbZynqs0N4K6R/
				EoGjHHkG2xgSgHTpeHbs0YYzQbdJo63m5w== )
ns1.nic.fr.		172800 IN RRSIG	A 8 3 172800 (
				20180221220313 20180123084323 64491 nic.fr.
				Rnwhloou1+lYWji0oVvMrODRsank5EHRLDN85WVXv4JW
				z2fHI+5IZLWaGlUProhkwqfobH0rjWFA/phPkhL0Bije
				gfhTGpQNheD5BN8MfPEMxYYQgZ7O/V6bWGh3M+IezrZv
				rBESOBpCnGbdadxJvUlZAmaYWJ2AL1wKYQ6OWP/viz0X
				AfIE6qxWfGa4xG3LrEWSL7Y+RFrM41TaY+Dd2fEnOJbo
				pUXtd6EC871zxdmzUQJbcpjWxKzXN4qysfSsk+T8H1my
				R4OnbczneKb/EmAfII6BMblJyuTyVnHu+3Q0Yd8NaXtE
				Sg1rL+bKwIowuIzW5wbnMRU8dQs5axgEGA== )
ns1.nic.fr.		172800 IN RRSIG	AAAA 8 3 172800 (
				20180219001645 20180120004323 64491 nic.fr.
				ikRbTnsIqZ6s+i/QTyALVrOtdY68VtPZFyD56V0RzoTB
				ZPBM25OCRERAPbNSBpStTnsUL8v8bSwV/L1kcL5dkZNz
				C/TJyhZtSJHVUAUi2ngOF2BjzjF3o2L7+44Ke1vnCGmv
				ObjJdjYMa9AK+/ybhvecLQ67+I84gN9v+srLmpGTeOIh
				Zebzj4QKWe97GHWbzF2CroAynJg3efEaU/WTXf6lhHIW
				/Tytwg1voUja/oWL55ABO6rjcMghYI/t81iBf/kwstmq
				Mo6PxeiT9UKS9b18Kh2vOGmcsP3b5+L3Kz4OW1ujFV37
				aklHXJbQCMcrFGH5VFO9cHoKlJxOIxSpSw== )
ns2.nic.fr.		172800 IN RRSIG	A 8 3 172800 (
				20180218140517 20180119224323 64491 nic.fr.
				FLsCHaSy4D2o0ScOmuRb7jb2BuKuh5bXIokv/wHHSjcr
				h95xA5HDToX4iP9vTplnkFPl1MNNMOKob7wB51+n6w5i
				DX/WecFhktOm41M/a0RXt0FUv4YRCnWKWjGZ23pqpsO4
				W7aQvk9MYVqQbjJacEyfGzeDjlYSzXwkiH4dOONFeNs6
				VoE6ihnRm+9pOKReyyr50tro7PcMakIXI8S0B9wGT2y8
				kRPLTcrsDobLnVCL+1H2bH0pA068n/YOPih1QZLa2Pw6
				RzzypcGECRuSxm34spNSD06/gfyjRPao78cMPW/dN3Fc
				1Yp7jbdX6gJ28TnmhTSFfj0xdZaBNDR0Ig== )
ns2.nic.fr.		172800 IN RRSIG	AAAA 8 3 172800 (
				20180216033932 20180117084323 64491 nic.fr.
				QI1REwIzT+XKk1vfRT3vBeoOvJtc8raJO/8Gv4AJQQBF
				MHEEvNuMiKYG7KCP4sBomh3YGgQdlKe/yWpoSIfdpg9b
				naLoFXxl+aPMLEEOihgkONUIsp/D4f16xlR03vWRYPYr
				vAUZCjblJ1Drb9ht9UoX5wiWuJIfhU8hjRm0kAE3duE4
				mNAHbHbr2diCyFEVHiqXT9360gB9XET3PWprJoLzsn+R
				N+fyTMAEruOeWVH8J3+MxrzdBKyxCS5dzUml0iPlcFr+
				G5sAa4XdZK5ja2kMHuPfuIQj8C83GzPj1ZrRLpmjEpb1
				DE9xnZO4obIkiAhmvB1J65CDi/2KEj5MeA== )
ns3.nic.fr.		172800 IN RRSIG	A 8 3 172800 (
				20180217182034 20180119004323 64491 nic.fr.
				KmEbNRoN4hIRNIqoJGOTgUfviyVQ9120n21/Rs4/Io5u
				snCdSWCTvf/D3Hha/LgZJorAmrREg7bBUxUaa3cnfIDh
				YGOYFKR/2MX0X6Deto7SZQmE/v9US/4OEdw3Ljt3a+Wf
				2wpEskAEghShiGyx6FxjC8e/u7k0+ezoj6LQ937EChmQ
				8mbQ1lqGTjyNAYdjnMX4Xn+lMLZS/Pdakjfe8R2+v83b
				r3kR/CaUDe83XyQcEquuZxc1ZAJRlxU9zf6eipIm2vaK
				oQUhlfY9nY1lh26YWOieUOc3lRXc4WGUTJD2COhKqzAH
				LXMilBwDaFyKzCKKjaEDYgXzBfzXbH+5Kg== )
ns3.nic.fr.		172800 IN RRSIG	AAAA 8 3 172800 (
				20180217223849 20180119024323 64491 nic.fr.
				IHcI0GyJuHGaEVRKih40IEVtVRiAR6RcMvLoNVAhXfj4
				7zjOdglQVSrRo0/S+rWCH7d09XLpr41lzcQH6OpDFlMT
				Mvo7Qmznpq9Ji9UpZxVLvTmsjtE5jyeZLBzCct3BPz8J
				ArszsygEpdKz4uKI8OM6xu7NMb/ALTaNgOo0zLYSe8xh
				VRniLMmfr0yGN9iPD6Jex4Dx4YpyEQ0v4V0kxyHzY5M0
				FS0naX7PdsF+0rnQ2J89LutYrT+v2P8lmGSSK1EWNbyM
				dDvxn95aWmcEy797jjETaJb/fn/+ZjFf44mBYXX6e44I
				rvGNUIN3M7+Xbim7AW0gcukrL3Z/S5/J9g== )
ns6.ext.nic.fr.		172800 IN RRSIG	A 8 4 172800 (
				20180217143618 20180118084323 64491 nic.fr.
				D1KGzW/W3KxrqCw0w8t0u7sLVwwYc5xcrGkdpc85ww5z
				EKEWKCx8VvfjAboeVaRgUK28Dz5YbNU7IAecGjY1I8+k
				5uoVRXltm7M10Hj8lrsMn5CCnn+GUM86yBHX3d5TTYI7
				fhyYOV5JBcA4HHX2i9DIUu3NucXFFIk3DeZtcDJO8G4H
				/6SUQW3Dh/ro2SoVjYLwuCUv/Fxj38hSMjBhcOcTRsD9
				Id+8nKSkwearfP1T6TwTCeyOFOyzpLD7F2voEgOP9hmc
				IRHNPCEcBz5bG1lNK7rGlHRtX7AfXzxR7679Izu1KYfX
				3cD+dhAzP+tX+O/UHEEf57gR2jKp1TzHcw== )
ns6.ext.nic.fr.		172800 IN RRSIG	AAAA 8 4 172800 (
				20180220151403 20180122004323 64491 nic.fr.
				eao2DZ3WqSdUU+uY/etN6HD+Ior6+TbxMYyNvODVTJMy
				j3+W01c1bufanNDDd1LGzLy3ZcFXzvywkD5gdh1+ehk0
				8XfP2gVkguQT3ofzO5qhFQw4esmtFczVzpHc+Zkjc1uu
				9cQ6MZvvVp6H+ndgAipKgB+siQvHQ1wnXhUaiL7RAU8b
				ittpsr1yjweKDiKCF0NGKyhe3ALDqin7/PQRFZ40l87Y
				vZxloZL9lwb+L/TiWr8lm+iGrHuqHkxCpXrIDKX7GwZL
				cj4rggFVS+jwjFYZdeDYmVo9HamYL2b+PYMt+/PJlRBg
				ccuvVmZyCiEyeLC4tjCoHfMWHjJZW+cAHQ== )

;; Query time: 11 msec
;; SERVER: 2001:660:3005:1::1:2#53(2001:660:3005:1::1:2)
;; WHEN: Thu Jan 25 15:47:08 UTC 2018
;; MSG SIZE  rcvd: 4238

(Same thing with the two other authoritative name servers.)

To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information