Top ISPs Report

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Here's the latest quarterly report from Network World and Visual Networks as we look at the top ISPs in the market. Through statistical analysis of Visual's Internet BenchMark data for dial-up service, we ranked the top ISPs in the business-to-business, national and regional markets, as they compare with other vendors within the same market. We've also included results for the past six months, to show whether an ISP's ranking this month has spiked or is consistently above average.

The marketplace seems to be tightening up. In September, AT&T's WorldNet service stayed on top in the national retail market, performing above the industry average in three out of the nine categories tested. BellSouth and SBIS shared the top spot in the regional retail market, and AT&T's Global Network Service (GNS) and UUNET's GridNet service tied for the lead in the business-to-business market. As always, you can check out monthly reports on Network World Fusion.

The data for this report comes from Visual Networks. Through its Internet Benchmark data, Visual Networks rates national, regional and business-to-business ISPs according to several factors, including call failure rate, modem connect speed and Web download performance. We took the raw data from Visual Networks and applied statistical analysis to rate the relative performance of each ISP. First, we derived the standard deviation of the numbers in each performance category. Standard deviation is a measure of how far the numbers in a series diverge from each other.

For each category in which an ISP performed better than one standard deviation from the industry mean, we award it one point. If the ISP did better than two standard deviations from the mean, we awarded it two points. Similarly, if an ISP did worse than the industry mean by more than one standard deviation, we took a point away from its score. If it did significantly worse, meaning two or more standard deviations, we took away two points. We started with a baseline of 12 points, so if an ISP scores 0 points it ends up with an adjusted score of 12.

After we scored each category, we summed the results to get a number that indicated the reliability and performance of each ISP.

A rating of 12 means an ISP was about even with its peers, or the industry average. In September, nine ISPs scored higher than 12 and six ISPs were average. The bad news, however, is that 12 ISPs scored less than 12 points.

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Quick Tips

DNS lookup

Throughput and connection speed aren't the end of the story when determining network performance. Domain Name System (DNS) performance adds additional overhead to almost any network activity. DNS translates host names like www.yahoo.com into IP addresses used by Internet routers. For example, when you open a Yahoo page, your browser requires at least one DNS lookup to complete before it can request the data for that page.

A typical DNS request is about 80 bytes in size, taking about 15 msec to squeeze through a 56K bit/sec line to your ISP. Responses vary, ranging from about 100 to 400 bytes in size and taking 15 msec to 70 msec to return. On top of this, each ISP's performance will differ based on how its DNS infrastructure is deployed.

The impact of DNS performance can be fairly complex. Local DNS lookup caches are maintained by Windows and other operating systems. These speed lookups when the same host name is requested repeatedly. DNS servers also maintain caches, ensuring that DNS queries for heavily used Web sites will often be answered quickly. In addition, each Web page may contain several objects from different servers - or all the objects could be from the same server, maximizing the effectiveness of a local cache.

September 2000 Top ISPs, by category
ISPScore*Strengths
National retail
AT&T WorldNet15Low CFR %** (all three), initial modem connect speed, average time to log on, average Web throughput
MindSpring13Average time to log on
MSN13Low Web fail/timeout percentage
Verizon-West13Low Web fail/timeout percentage
Regional retail
BellSouth14Low CFR% (business), high initial modem connect speed
SBIS14Low CFR% (evening), low Web fail/timeout percentage
Ameritech13Low CFR% (24-hour, evening)
Business-to-business
AT&T (GNS)13Average time to log on
UUNET (Gridnet)13Average time to log on
*12 = aver.        **CFR = call failure rate

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Month-to-month comparison
ISPAprilMayJuneJulyAug.Sept.
AT&T WorldNet161820201615
BellSouth121113141214
SBIS61112111114
Ameritech151411121513
AT&T (GNS)131115151413
MindSpring91313131313
MSN11104121113
UUNET (GridNet)1316118713
Verizon-West121112111213

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Industry averages for September 2000
CategoryNational retailRegional retailBusiness-to-businessTop ISP in category
24-hour CFR %3.30%2.70%9.70%Ameritech
Evening-hour CFR %4.70%3.00%10.40%Ameritech
Business-hour CFR %3.60%3.50%11.20%Verizon-North
Initial modem speed (K bit/sec)47.7648.0947.94BellSouth
Avg. time to log on (sec)29.6631.2331.5AT&T WorldNet
Avg. DNS lookup (msec)468.92657.94584.73PSI
Avg. Web throughput (K bit/sec)4.494.824.64PacBell
Avg. download time (sec)23.0123.224.89AOL
Avg. total Web fail %1.20%1.20%1.40%SBIS

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