School of Electrical Engineering and Computer Science, 2004 Slide 1

Autonomic DNS

Experiment Architecture, Symptom and Fault Identification

School of Electrical Engineering and Computer Science, 2004 Slide 2

Experiment Architecture Physical system setup

• Three Dell workstations running Redhat Linux 9.0, configured on an isolated network via IP Tables.

• The network resides on the Computer Science Research network

Logical Domain Name System• Two Root servers controlling two top level domains:

• .example

• .test

• Six sub-domains• red.test, yellow.test, green.test

• white.example, orange.example, black.example

School of Electrical Engineering and Computer Science, 2004 Slide 3

Experiment Architecture

All instances of the DNS will consist of Bind 9.2.3 Each domain will consist of one master DNS. Each domain will have 0 to 5 slave DNS.

• Master (red) – ns.red.test

• Slave (red) – ns.yellow.test, ns.green.test, ns.white.example, ns.orange.example, ns.black.example

• Master (yellow) – ns.yellow.test

• Slave (yellow) – ns.green.test, ns.white.example, ns.orange.example, ns.black.example

From the examples above, each zone will have n-1 slave

name servers assigned to it. The last name server will be

without a slave.

School of Electrical Engineering and Computer Science, 2004 Slide 4

Experiment Architecture

Having a varied number of slave name servers associated with the master name servers will allow us to test issues ranging from server performance on various levels to multiple user issues.

The experiments conducted will consist of the symptoms identified on the following slides

School of Electrical Engineering and Computer Science, 2004 Slide 5

DNS Symptoms

Loss of Network Connectivity Response from unexpected source Recursion Bugs Client unsure on handling of NS record in

authority section No answer to query Client calls on server too many times Name server is infected with bogus cache

data

School of Electrical Engineering and Computer Science, 2004 Slide 6

DNS Symptoms

A server refers to itself in the authority section Cache leaks Remote names can’t be looked up Name error bugs Lookups take a long time Wrong or Inconsistent Answer Slave name server data does not change

when master server zone data changes Is invalid proceeding anyway

School of Electrical Engineering and Computer Science, 2004 Slide 7

DNS Symptoms

Slave server can’t load zone data Internet services refused Host fails authentication checks Inconsistant or missing bad data Lame server reported Name server fails to load Name server reports “Too many open files”

School of Electrical Engineering and Computer Science, 2004 Slide 8

DNS Faults

Forgot to increment serial number Forgot to reload primary master server after changes

are made Corrupt server cache Ignored referral To many referrals Malicious server Zero answer Added name to db file, but forgot to add PTR record

School of Electrical Engineering and Computer Science, 2004 Slide 9

DNS Faults

Name server cache set too small Server does not do negative caching Syntax error in zone data file on master Incorrect IP address for master on slave zone

data file Syntax error in configuration file or zone data

file Missing dot at end of a domain name in zone

data file

School of Electrical Engineering and Computer Science, 2004 Slide 10

DNS Faults

Missing root.hints/db.cache data file Missing subdomain delegation TTL exceeded Syntax error in resolv.conf Incorrect labels in DNS name Incorrect SOA format Incorrect Glue records Retry interval is set too low in SOA

School of Electrical Engineering and Computer Science, 2004 Slide 11

DNS Faults

Incorrect address in query list – allow-query { address_match_list; };

Incorrect configuration named.conf listen-on { ip_address; };

PTR record points to CNAME Expire time exceeded Loss of network connectivity

School of Electrical Engineering and Computer Science, 2004 Slide 12

Symptom/Fault Matrixf1 f2 f3 f4 f5 f6 f7 f8 f9 f10 f11 f12 f13 f14 f15 f16 f17 f18 f19 f20 f21 f22 f23 f24 f25 f26 f27

s1 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0s2 0 1 0 0 0 0 0 0 0 0 1 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0s3 0 0 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0s4 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0s5 0 0 0 0 0 0 0 0 0 0 1 0 0 1 1 0 0 1 0 0 0 1 1 0 0 1 0s6 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0s7 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0s8 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0s9 0 0 1 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0s10 0 0 0 0 0 0 1 0 0 0 0 0 0 1 1 0 1 1 0 1 0 0 0 0 0 1 1s11 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1s12 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 1 0 0 1 1 0 0 0 0 0s13 0 1 0 0 0 1 1 0 0 0 0 1 1 0 0 0 1 1 0 1 1 0 0 0 0 1 0s14 1 1 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0s15 0 1 0 0 0 0 0 0 0 0 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0s16 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0s17 0 1 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1s18 1 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0s19 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0s20 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 1 0 1 0 0 0 1 0 0s21 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0s22 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0s23 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0Sy

mpt

oms

Faults