## Solution - Follow the Pipes

by Megan Russell, Arshia Surti, Heather Sweeney, and Hosea Siu

The first step is to discover that all of the cities are home to IPV4 DNS root servers. The interactive map at http://www.root-servers.org/ can be used to find server information. For example, Quezon City hosts a DNS root server at 192.58.128.30.

The next step (still using Quezon City as an example) is to apply the indexing instructions "4(4+1)_(1-6)(1-6)3" to the root server ip address. Taking it as "digit 4, digit 4 + digit 1, digit 1 - digit 6, digit 1 - digit 6, digit 3" gives 5, 6, 0, 0, 2 for room 56-002.

Upon going to building 56 and visiting room 56-002, the solver will see a marked pipe exiting the room. That pipe continues on to one of the non-numbered rooms, in this case room 16-065 corresponding to Fussa. The marker on the pipe end in 56-002 indicates the subway lines (on the map) used to connect the two cities. In this case the list is red, blue, orange, pink, red.

Tracing out a route between Quezon City and Fussa on the subway map by following those five colored lines in order draws the letter O.

The full set of data:

Starting City IP
Index
Room
Ending City IP
Index
Room
Colors Letter Drawn On Map
Quezon City 192.58.128.30
4(4+1)_(1-6)(1-6)3
56-002
Fussa 192.112.36.4
48_(1-5)8(8-1)
16-065
Red
Blue
Orange
Pink
Red
O
San Diego 198.97.190.53
95_881
57-001
Winnipeg 199.7.91.13
8(1+6)_(1-6)38
32-093
Red
Pink
Orange
Purple
N
Budapest 193.0.14.129
6_482
4-029
Bouake 199.7.83.42
5_(3-2)(3-2)6
8-003
Orange
Blue
L
Lulea 192.36.148.17
3_(2-2)(3-3)5
2-006
Caracas 192.5.5.241
3_(5-4)1(2-1)
2-018
Black I
Naples 192.112.36.4
4(5-4)_(5-4)87
10-063
Aberdeen 198.97.190.53
18_898
10-050
Purple
Orange
Pink
Red
N
Kansas City 193.0.14.129
13_14(5+6)5
13-1051
Noida 193.0.14.129
13_4144
13-0100
Grey
Purple
Pink
Black
Blue
E
Mahe 199.7.83.42
2_(3-2)(7+1)(7+1)
9-055
Noida 193.0.14.129
13_4144
13-0100
Purple
Pink
Black
Blue
P
Porto 199.7.83.42
6_(2-3)16
3-013
Poznan 193.0.14.129
3_4(1+5)4
3-020
Orange
Pink
Purple
Blue
O
Berlin 199.7.91.13
84_(3-2)(4-1)1
37-061
Manama 192.36.148.17
4(2-3)_(6-1)87
37-084
Red
Pink
Orange
Blue
Green
R
Stuttgart-Vaihingen 192.112.36.4
39_(4-1)91
24-040
Phnom Penh 192.5.5.241
37_(1-8)14
24-015
Purple
Pink
Black
N