I have a name server for the few domains I host and my little local LAN. with reverse DNS lookup on for incoming e-mail and for web server logging, it does a fair bit of ns queries. I considered making it forward to concentric (my DSL ISP) name server but the result would be degraded performance of my network (or possibly no improvement over concentric, depending on which root is queried): PING hudson.concentric.net (207.155.183.72): 56 data bytes 64 bytes from hudson.concentric.net (207.155.183.72): seq=0 ttl=247 time=85.1 ms . 64 bytes from hudson.concentric.net (207.155.183.72): seq=1 ttl=247 time=85.9 ms . 64 bytes from hudson.concentric.net (207.155.183.72): seq=2 ttl=247 time=86.3 ms . ---- hudson.concentric.net (207.155.183.72) PING Statistics ---- 3 packets transmitted, 3 packets received, 0% packet loss round-trip (ms) min/avg/max = 85.1/85.8/86.3 (std = 0.475) PING a.root-servers.net (198.41.0.4): 56 data bytes 64 bytes from a.root-servers.net (198.41.0.4): seq=0 ttl=249 time=28.9 ms. 64 bytes from a.root-servers.net (198.41.0.4): seq=1 ttl=249 time=19.2 ms. 64 bytes from a.root-servers.net (198.41.0.4): seq=2 ttl=249 time=18.0 ms. 64 bytes from a.root-servers.net (198.41.0.4): seq=3 ttl=249 time=48.6 ms. PING b.root-servers.net (128.9.0.107): 56 data bytes 64 bytes from b.root-servers.net (128.9.0.107): seq=0 ttl=248 time=73.1 ms. 64 bytes from b.root-servers.net (128.9.0.107): seq=1 ttl=248 time=72.5 ms. 64 bytes from b.root-servers.net (128.9.0.107): seq=2 ttl=248 time=73.7 ms. 64 bytes from b.root-servers.net (128.9.0.107): seq=3 ttl=248 time=73.3 ms. 64 bytes from b.root-servers.net (128.9.0.107): seq=4 ttl=248 time=76.9 ms. ò ---- b.root-servers.net (128.9.0.107) PING Statistics ---- 5 packets transmitted, 5 packets received, 0% packet loss round-trip (ms) min/avg/max = 72.5/73.9/76.9 (std = 1.54) PING c.root-servers.net (192.33.4.12): 56 data bytes 64 bytes from c.root-servers.net (192.33.4.12): seq=0 ttl=247 time=23.4 ms. 64 bytes from c.root-servers.net (192.33.4.12): seq=1 ttl=247 time=20.8 ms. 64 bytes from c.root-servers.net (192.33.4.12): seq=2 ttl=247 time=22.7 ms. 64 bytes from c.root-servers.net (192.33.4.12): seq=3 ttl=247 time=20.2 ms. 64 bytes from c.root-servers.net (192.33.4.12): seq=4 ttl=247 time=20.6 ms. ò ---- c.root-servers.net (192.33.4.12) PING Statistics ---- 5 packets transmitted, 5 packets received, 0% packet loss round-trip (ms) min/avg/max = 20.2/21.5/23.4 (std = 1.25) PING d.root-servers.net (128.8.10.90): 56 data bytes 64 bytes from d.root-servers.net (128.8.10.90): seq=0 ttl=246 time=91.7 ms. 64 bytes from d.root-servers.net (128.8.10.90): seq=1 ttl=246 time=109 ms. 64 bytes from d.root-servers.net (128.8.10.90): seq=2 ttl=246 time=109 ms. 64 bytes from d.root-servers.net (128.8.10.90): seq=3 ttl=246 time=111 ms. 64 bytes from d.root-servers.net (128.8.10.90): seq=4 ttl=246 time=99.6 ms. ò ---- d.root-servers.net (128.8.10.90) PING Statistics ---- 5 packets transmitted, 5 packets received, 0% packet loss round-trip (ms) min/avg/max = 91.7/104/111 (std = 7.34) PING E.ROOT-SERVERS.NET (192.203.230.10): 56 data bytes 64 bytes from E.ROOT-SERVERS.NET (192.203.230.10): seq=0 ttl=56 time=75.1 ms. 64 bytes from E.ROOT-SERVERS.NET (192.203.230.10): seq=1 ttl=56 time=78.3 ms. 64 bytes from E.ROOT-SERVERS.NET (192.203.230.10): seq=2 ttl=56 time=75.0 ms. 64 bytes from E.ROOT-SERVERS.NET (192.203.230.10): seq=3 ttl=56 time=75.9 ms. ò ---- E.ROOT-SERVERS.NET (192.203.230.10) PING Statistics ---- 4 packets transmitted, 4 packets received, 0% packet loss round-trip (ms) min/avg/max = 75.0/76.0/78.3 (std = 1.35) Clearly BTW I'm not getting what I'm paying for (1.1Mb SDSL via Covad) from Concentric. 85ms is ridiculously bad to a name server.
I have a name server for the few domains I host and my little local LAN. with reverse DNS lookup on for incoming e-mail and for web server logging, it does a fair bit of ns queries. I considered making it forward to concentric (my DSL ISP) name server but the result would be degraded performance of my network (or possibly no improvement over concentric, depending on which root is queried):
PING hudson.concentric.net (207.155.183.72): 56 data bytes 64 bytes from hudson.concentric.net (207.155.183.72): seq=0 ttl=247 time=85.1 ms . 64 bytes from hudson.concentric.net (207.155.183.72): seq=1 ttl=247 time=85.9 ms . 64 bytes from hudson.concentric.net (207.155.183.72): seq=2 ttl=247 time=86.3 ms . ---- hudson.concentric.net (207.155.183.72) PING Statistics ---- 3 packets transmitted, 3 packets received, 0% packet loss round-trip (ms) min/avg/max = 85.1/85.8/86.3 (std = 0.475)
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Clearly BTW I'm not getting what I'm paying for (1.1Mb SDSL via Covad) from Concentric. 85ms is ridiculously bad to a name server.
What you're seeing isn't really too bad. --- a.root-servers.net ping statistics --- 5 packets transmitted, 4 packets received, 20% packet loss round-trip min/avg/max/stddev = 38.025/43.774/56.639/7.573 ms --- b.root-servers.net ping statistics --- 5 packets transmitted, 4 packets received, 20% packet loss round-trip min/avg/max/stddev = 89.725/98.950/115.136/10.337 ms su-2.00# --- c.root-servers.net ping statistics --- 5 packets transmitted, 4 packets received, 20% packet loss round-trip min/avg/max/stddev = 43.902/50.025/56.996/4.661 ms --- d.root-servers.net ping statistics --- 5 packets transmitted, 5 packets received, 0% packet loss round-trip min/avg/max/stddev = 78.115/99.506/125.723/17.295 ms su-2.00# --- e.root-servers.net ping statistics --- 5 packets transmitted, 5 packets received, 0% packet loss round-trip min/avg/max/stddev = 66.496/68.397/72.560/2.221 ms --- f.root-servers.net ping statistics --- 5 packets transmitted, 5 packets received, 0% packet loss round-trip min/avg/max/stddev = 86.751/88.591/90.156/1.445 ms hudson.concentric.net might be across the country from you, concentric is a big provider. Also keep in mind that ICMP pings aren't necessarily the best measurement of round-trip-time. Many ISP's now have their routers placing icmp at the bottom of the queue, causing icmp to get dropped if anything is going to. This also increases ping times, while real applications won't actually see it. Now, my uplink's name server happens to be sitting a few feet from where my lines reach them, so it's decently fast: --- cerebus.mcs.net ping statistics --- 5 packets transmitted, 5 packets received, 0% packet loss round-trip min/avg/max/stddev = 6.136/14.032/26.805/8.062 ms Also, don't confuse what you're paying for (bandwidth) with good connectivity. You can get 30ms pings back from hosts on a 64k line, and still be slow. Unless you're seeing a real problem, I wouldn't worry much about it. Personally, I disable reverse lookups on my web server, specifically for that reason. Even if I can get to my uplink's nameserver quickly, that doesn't necessarily mean the nameserver that's authoritative for the domain I'm looking up is going to respond quickly, or at all. Also, this probably doesn't belong on NANOG, as it's not a internet-wide operational discussion. There are some bind/named mailing lists I can point you to if you need more help. -- Kevin
participants (2)
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Dana Hudes -
Kevin Day