Timeout issues - Suggestions / Solutions?

[David Hekimian]

In working to debug another problem with some others, I've noticed that I'm
unable to do a MX query for Lycos.Com without it timing out. Upon trying to
deliver mail to Lycos.com, it times out getting a MX record for Lycos.com
and thus does a A record lookup for Lycos.Com. This ends up causing issues
as the mailing list software tries to deliver e-mail to Lycos.com @
209.202.192.30 which is NOT a mail server.

Each time I run my test, I restart named beforehand to flush the cache.

In the example below, I had to extend the timeout to 20 seconds as the query
took 19956 msec to complete. I did the same query with HotMail.Com and it
took 493 msec.


Any reason why it would take so long to receive a result from Lycos.com?

Does it have to do with the query being too large for TCP and its switching
to UDP?

How can I check each Lycos NS to see if its a specific name server that is
causing the timeout issue?

What can be done to reduce the lookup time besides pre caching?
	Ask Lycos to reduce the size of their MX list?



My Setup: RedHat 7.2, Bind 8.3.1, T1 with UUnet.

- David


dig -t mx +debug +d2 +time=20 lycos.com

; <<>> DiG 8.3 <<>> -t +debug +d2 +time=20 lycos.com 
;; res_nmkquery(QUERY, lycos.com, IN, MX)
;; res options: init debug recurs defnam dnsrch ?0x80000000?
;; res_send()
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 23280
;; flags: rd; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0
;; QUERY SECTION:
;;      lycos.com, type = MX, class = IN

;; Querying server (# 1) address = 127.0.0.1
;; new DG socket
;; truncated answer
;; Querying server (# 1) address = 127.0.0.1
;; got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 23280
;; flags: qr rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 5, ADDITIONAL: 20
;; QUERY SECTION:
;;      lycos.com, type = MX, class = IN

;; ANSWER SECTION:
lycos.com.              1H IN MX        10 mx4.mail.lycos.com.
lycos.com.              1H IN MX        10 mx1.mail.lycos.com.
lycos.com.              1H IN MX        10 mx2.mail.lycos.com.
lycos.com.              1H IN MX        10 mx3.mail.lycos.com.

;; AUTHORITY SECTION:
lycos.com.              1H IN NS        ns1.hotwired.com.
lycos.com.              1H IN NS        ns2.hotwired.com.
lycos.com.              1H IN NS        ns3.hotwired.com.
lycos.com.              1H IN NS        ns4.hotwired.com.
lycos.com.              1H IN NS        ns5.hotwired.com.

;; ADDITIONAL SECTION:
mx4.mail.lycos.com.     1H IN A         209.185.123.129
mx4.mail.lycos.com.     1H IN A         209.185.123.151
mx4.mail.lycos.com.     1H IN A         209.185.123.149
mx4.mail.lycos.com.     1H IN A         209.185.123.126
mx4.mail.lycos.com.     1H IN A         209.185.123.198
mx4.mail.lycos.com.     1H IN A         209.185.123.123
mx4.mail.lycos.com.     1H IN A         209.185.123.197
mx2.mail.lycos.com.     1H IN A         209.185.123.148
mx2.mail.lycos.com.     1H IN A         209.185.123.130
mx2.mail.lycos.com.     1H IN A         209.185.123.152
mx2.mail.lycos.com.     1H IN A         209.185.123.147
mx3.mail.lycos.com.     1H IN A         209.185.123.124
mx3.mail.lycos.com.     1H IN A         209.185.123.199
mx3.mail.lycos.com.     1H IN A         209.185.123.127
mx3.mail.lycos.com.     1H IN A         209.185.123.128
ns1.hotwired.com.       1d23h59m40s IN A  209.202.224.253
ns2.hotwired.com.       1d23h59m40s IN A  209.202.220.8
ns3.hotwired.com.       1d23h59m40s IN A  209.202.228.10
ns4.hotwired.com.       1d23h59m40s IN A  209.202.221.55
ns5.hotwired.com.       1d23h59m40s IN A  209.202.193.252

;; Total query time: 19956 msec
;; FROM: CorpDNS to SERVER: default -- 127.0.0.1
;; WHEN: Thu May 23 15:23:38 2002
;; MSG SIZE  sent: 27  rcvd: 531



dig -t mx +debug +d2 +time=20 hotmail.com

; <<>> DiG 8.3 <<>> -t +debug +d2 +time=20 hotmail.com 
;; res_nmkquery(QUERY, hotmail.com, IN, MX)
;; res options: init debug recurs defnam dnsrch ?0x80000000?
;; res_send()
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 22088
;; flags: rd; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0
;; QUERY SECTION:
;;      hotmail.com, type = MX, class = IN

;; Querying server (# 1) address = 127.0.0.1
;; new DG socket
;; got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 22088
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 14, AUTHORITY: 4, ADDITIONAL: 7
;; QUERY SECTION:
;;      hotmail.com, type = MX, class = IN

;; ANSWER SECTION:
hotmail.com.            1H IN MX        5 mx10.hotmail.com.
hotmail.com.            1H IN MX        5 mx11.hotmail.com.
hotmail.com.            1H IN MX        5 mx12.hotmail.com.
hotmail.com.            1H IN MX        5 mx13.hotmail.com.
hotmail.com.            1H IN MX        5 mx14.hotmail.com.
hotmail.com.            1H IN MX        5 mx15.hotmail.com.
hotmail.com.            1H IN MX        5 mx01.hotmail.com.
hotmail.com.            1H IN MX        5 mx02.hotmail.com.
hotmail.com.            1H IN MX        5 mx04.hotmail.com.
hotmail.com.            1H IN MX        5 mx05.hotmail.com.
hotmail.com.            1H IN MX        5 mx06.hotmail.com.
hotmail.com.            1H IN MX        5 mx07.hotmail.com.
hotmail.com.            1H IN MX        5 mx08.hotmail.com.
hotmail.com.            1H IN MX        5 mx09.hotmail.com.

;; AUTHORITY SECTION:
hotmail.com.            1H IN NS        ns1.hotmail.com.
hotmail.com.            1H IN NS        ns2.hotmail.com.
hotmail.com.            1H IN NS        ns3.hotmail.com.
hotmail.com.            1H IN NS        ns4.hotmail.com.

;; ADDITIONAL SECTION:
mx10.hotmail.com.       1H IN A         64.4.49.135
mx11.hotmail.com.       1H IN A         64.4.49.199
mx12.hotmail.com.       1H IN A         64.4.50.7
mx13.hotmail.com.       1H IN A         64.4.50.71
mx14.hotmail.com.       1H IN A         65.54.232.7
mx15.hotmail.com.       1H IN A         65.54.232.71
mx01.hotmail.com.       1H IN A         64.4.55.71

;; Total query time: 493 msec
;; FROM: CorpDNS to SERVER: default -- 127.0.0.1
;; WHEN: Thu May 23 16:05:12 2002
;; MSG SIZE  sent: 29  rcvd: 507