 jlivingoodPremium,VIP
join:2007-10-28
Philadelphia, PA
kudos:1 | reply to iansltx
Re: Why said by iansltx:Some CDN-based services work better when you have local DNS. For example Akamai has a cache here in Denver. Comcast DNS points to this cache, which serves up content while directly connected to Comcast's network, thus saving Comcast money. If you use other DNS services, you'll get a different Akamai endpoint and lower performance. You are spot on regarding performance.
Many websites use Content Delivery Networks to distribute their content more efficiently across Internet Service Providers by pushing the content closer to the end user. Comcast's DNS should send users to the closest content servers to the customer, resulting an a speedier experience. Give it a try yourself with CDN-based content --> try with names like cdn.netflix.com or www.comcast.net for example (compare results from our cache vs. some other server).
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JL
Comcast |
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jlivingoodPremium,VIP
join:2007-10-28
Philadelphia, PA
kudos:1 | I am in Philly... So for example I might ask how is performance to cdn.netflix.com?
Comcast DNS in Philadelphia, PA (68.87.64.150)
netflix.vo.llnwd.net.
208.111.160.6
208.111.161.254
PING 208.111.160.6
64 bytes from 208.111.160.6: icmp_seq=0 ttl=50 time=11.169 ms
64 bytes from 208.111.160.6: icmp_seq=1 ttl=50 time=8.923 ms
64 bytes from 208.111.160.6: icmp_seq=2 ttl=50 time=8.738 ms
64 bytes from 208.111.160.6: icmp_seq=3 ttl=50 time=11.508 ms
64 bytes from 208.111.160.6: icmp_seq=4 ttl=50 time=8.057 ms
--- 208.111.160.6 ping statistics ---
5 packets transmitted, 5 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 8.057/9.679/11.508/1.389 ms
Then, let's check against DNS @ 4.2.2.1
QUESTION SECTION:
cdn.netflix.com. IN A
ANSWER SECTION:
cdn.netflix.com. 1671 IN CNAME netflix.vo.llnwd.net.
netflix.vo.llnwd.net. 31 IN A 208.111.148.7
netflix.vo.llnwd.net. 31 IN A 208.111.148.6
PING 208.111.148.7
64 bytes from 208.111.148.7: icmp_seq=0 ttl=44 time=86.473 ms
64 bytes from 208.111.148.7: icmp_seq=1 ttl=44 time=85.991 ms
64 bytes from 208.111.148.7: icmp_seq=2 ttl=44 time=86.000 ms
64 bytes from 208.111.148.7: icmp_seq=3 ttl=44 time=86.002 ms
64 bytes from 208.111.148.7: icmp_seq=4 ttl=44 time=85.668 ms
--- 208.111.148.7 ping statistics ---
5 packets transmitted, 5 packets received, 0.0% packet loss
round-trip min/avg/max/stddev = 85.668/86.027/86.473/0.257 ms
YMMV but you get the idea.
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JL
Comcast |
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| As a sysadmin myself your dead on. Despite what people say, I stick with the ISP's DNS. I do use OpenDNS at work, but that's a commercial bonded multi-T1 connection. |
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 beerbumobscurum per obscuriusPremium
join:2000-05-06
Eastern PA | reply to jlivingood
I run my own DNS server, and it just so happens I get the same IP's (for netflix at least) as the Comcast servers - that is when the servers actually work..
C:\>nslookup
Default Server: UnKnown
Address: 192.168.1.5
> cdn.netflix.com
Server: UnKnown
Address: 192.168.1.5
Non-authoritative answer:
Name: netflix.vo.llnwd.net
Addresses: 208.111.160.6
208.111.161.254
Aliases: cdn.netflix.com
> server 68.87.64.146
Default Server: [68.87.64.146]
Address: 68.87.64.146
> cdn.netflix.com
Server: [68.87.64.146]
Address: 68.87.64.146
Non-authoritative answer:
Name: netflix.vo.llnwd.net
Addresses: 208.111.160.6
208.111.161.254
Aliases: cdn.netflix.com
> server 68.87.96.4
Default Server: phildns2.inflow.pa.bo.comcast.net
Address: 68.87.96.4
> cdn.netflix.com
Server: phildns2.inflow.pa.bo.comcast.net
Address: 68.87.96.4
DNS request timed out.
timeout was 2 seconds.
DNS request timed out.
timeout was 2 seconds.
DNS request timed out.
timeout was 2 seconds.
DNS request timed out.
timeout was 2 seconds.
*** Request to phildns2.inflow.pa.bo.comcast.net timed-out
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The good may die young, pricks live forever... |
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 ctg1701aVIP
join:2008-08-07
Philadelphia, PA
1 edit | 68.87.96.3 and 68.87.96.4 were decomissioned over a year ago. Please look at »dns.comcast.net for the most valid list of DNS for Comcast.
Thanks |
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beerbumobscurum per obscuriusPremium
join:2000-05-06
Eastern PA | said by ctg1701a:68.87.96.3 and 68.87.96.4 were decomissioned over a year ago. Please look at » dns.comcast.net for the most valid list of DNS for Comcast. Thanks then why are they still showing up when using dhcp? this is why I started running my own DNS, the servers issued by dhcp did not work.
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The good may die young, pricks live forever... |
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ctg1701aVIP
join:2008-08-07
Philadelphia, PA | said by beerbum:said by ctg1701a:68.87.96.3 and 68.87.96.4 were decomissioned over a year ago. Please look at » dns.comcast.net for the most valid list of DNS for Comcast. Thanks then why are they still showing up when using dhcp? this is why I started running my own DNS, the servers issued by dhcp did not work. No DHCP server should be handing those addresses out. Can you PM me with the DHCP server you are getting these from and what IP space you are getting so I can look at the subnet settings?
Thanks
Thanks |
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Reviews:
 ·Comcast
| reply to jlivingood
That is interesting.
According to what I know about akamai their mapping software makes up for this. They do test dns servers when mapping.
The fastest replies get the route. If it's costing comcast money , then may I suggest you get a better route ?
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"It's always funny until someone gets hurt......and then it's absolutely friggin' hysterical!" |
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jlivingoodPremium,VIP
join:2007-10-28
Philadelphia, PA
kudos:1 | said by BosstonesOwn:That is interesting. According to what I know about akamai their mapping software makes up for this. They do test dns servers when mapping. The fastest replies get the route. If it's costing comcast money , then may I suggest you get a better route ? If you look at the data I posted, our DNS provides a superior answer. (So not sure what you mean about getting a better route.)
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JL
Comcast |
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Reviews:
·Comcast
| I was answering in regards to the akamai software.
Mapper runs according to pings and other functions.
If your dns server answers slower then another then the route gets shifted to let the user get the content faster.
The same with servers. If the content is in Chicago and mapper detects the user is in Chicago but the route is congested mapper will let the user get pushed to say New York , to get the download and content quicker. Which is why Akamai moving gear into every pop they can get space in is a major win for the providers , but the content can still sometimes be gotten from a faster route even if it's half way across the country.
So again , if the links are congested maybe you need a better route 
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"It's always funny until someone gets hurt......and then it's absolutely friggin' hysterical!" |
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