Top ISPs Report

Here's our 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 (see How We Did It), we ranked the top ISPs in the business-to-business, national and regional ISPs, as they compare to other vendors within the same market. We've also included results for the past six months, to show whether an ISPs ranking this month has spiked or is consistently above average.

In October 2000, AT&T's WorldNet service continued to top the national retail market, performing above the industry average in four out of nine categories tested. The regional retail market continued to be strong, with Ameritech taking the top spot, but with Verizon-North, BellSouth and SBIS close behind. Finally, AT&T's Global Network Service (GNS) took the top position in the business to business market for October, with Concentric and UUNET's GridNet service close behind.

October 2000 Top ISPs, by Category
ISPScore Strengths
National Retail
AT&T WorldNet16 Initial modem connect speed, average time to login, average DNS lookup time, average Web throughput
MindSpring13 Average DNS lookup time
Regional Retail
Ameritech15 Low CFR% (all three areas), average DNS lookup time
Verizon-North14 Average time to login, average DNS lookup time
BellSouth13 Initial modem connect speed
SBIS13 Low CFR% (business hours)
AT&T (GNS)14 Average time to login, average DNS lookup time
Concentric13 Average DNS lookup time, average Web throughput
UUNET (GridNet)13 Average time to login
Month-to-month comparison
ISP May June July August September October
AT&T WorldNet 18 20 20 16 15 15
Ameritech 14 11 12 15 13 14
Verizon-North 9 12 10 11 10 14
AT&T (GNS) 11 15 15 14 13 14
MindSpring 13 13 13 13 13 13
BellSouth 11 13 14 12 14 13
SBIS 11 12 11 11 14 13
Concentric 15 15 14 14 12 13
UUNET (GridNet) 16 11 8 7 13 13
Industry Averages for October 2000
Category National retail Regional Retail B2B Top ISP
24-hour CFR% 4.80% 3.70% 11.60% Ameritech
Evening-hour CFR% 6.40% 4.00% 12.80% Ameritech
Business-hour CFR% 4.90% 3.30% 10.90% Ameritech
Initial modem speed (Kbps) 47.84 48.01 47.95 BellSouth
Avg. time to login (sec) 29.68 31.21 31.2 AT&T WorldNet
Avg. DNS lookup (msec) 516.93 537.03 645.15 Verizon-North
Avg. Web Tput (KB/s) 4.38 4.74 4.52 PacBell
Avg. download time (sec) 25.6 26.23 28.02 AOL
Avg. total Web fail % 0.70% 0.40% 1.30% MSN

How we did it

The data for this report comes from Visual Networks. Through its Internet Benchmark data, Visual rates national, regional and business-to-business Internet Service Providers according to several factors, including call failure rate, modem connect speed, and Web download performance.

We took the raw data from Visual 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 they end up with an adjusted score of 12.

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

A rating of 12 means an ISP was about even with its peer, or the industry average. In October, nine ISPs scored higher than 12 and seven ISPs were average. The bad news, however, is that 11 ISPs scored less than 12 points. A total of 27 ISPs were tested.

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 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.

This story, "Top ISPs Report" was originally published by Network World.

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