Requirements Specification
This document outlines the functional and non-functional requirements for the BIND DNS server deployment with TSIG authentication and Docker Compose orchestration.
Functional Requirements
Core DNS Functionality
ID
Requirement
Description
Priority
FR-001
DNS Resolution
The system SHALL provide authoritative DNS resolution for configured zones
High
FR-002
Zone Management
The system SHALL support creation, modification, and deletion of DNS zones
High
FR-003
Record Types
The system SHALL support standard DNS record types (A, AAAA, CNAME, MX, TXT, PTR, SRV, NS, SOA)
High
FR-004
Dynamic Updates
The system SHALL support dynamic DNS updates via RFC 2136
High
FR-005
Zone Transfers
The system SHALL support zone transfers (AXFR/IXFR) for secondary DNS servers
Medium
Security Requirements
ID
Requirement
Description
Priority
FR-006
TSIG Authentication
The system SHALL implement TSIG (RFC 2845) for authenticated DNS updates
High
FR-007
Key Management
The system SHALL provide secure generation and management of TSIG keys
High
FR-008
Access Control
The system SHALL restrict DNS updates to authenticated clients only
High
FR-009
Multiple Keys
The system SHALL support multiple TSIG keys for different clients/services
Medium
FR-010
Key Rotation
The system SHALL support TSIG key rotation without service disruption
Medium
Integration Requirements
ID
Requirement
Description
Priority
FR-011
External-DNS
The system SHALL integrate with Kubernetes External-DNS for automatic record management
High
FR-012
DNSControl
The system SHALL support DNSControl for declarative DNS configuration
Medium
FR-013
octoDNS
The system SHALL support octoDNS for multi-provider DNS synchronization
Medium
FR-014
CI/CD Integration
The system SHALL support automated DNS deployments via CI/CD pipelines
Medium
FR-015
API Access
The system SHALL provide programmatic access for DNS management
Low
Environment Management
ID
Requirement
Description
Priority
FR-016
Multi-Environment
The system SHALL support development, staging, and production environments
High
FR-017
Configuration Management
The system SHALL use environment files for configuration management
High
FR-018
Docker Deployment
The system SHALL deploy via Docker Compose for consistency
High
FR-019
Health Checks
The system SHALL provide health check endpoints for monitoring
Medium
FR-020
Backup/Restore
The system SHALL support backup and restore of DNS configurations
Medium
Non-Functional Requirements
ID
Requirement
Description
Target Value
Priority
NFR-001
Query Response Time
DNS queries SHALL be resolved within specified time limits
< 50ms (95th percentile)
High
NFR-002
Throughput
The system SHALL handle concurrent DNS queries
1000 QPS minimum
High
NFR-003
Update Latency
Dynamic DNS updates SHALL be processed within time limits
< 5 seconds
Medium
NFR-004
Zone Transfer Time
Zone transfers SHALL complete within reasonable time
< 60 seconds for 10K records
Medium
NFR-005
Startup Time
DNS server SHALL start and be ready for queries
< 30 seconds
Low
Availability Requirements
ID
Requirement
Description
Target Value
Priority
NFR-006
Service Uptime
The DNS service SHALL maintain high availability
99.9% uptime
High
NFR-007
Recovery Time
Service SHALL recover from failures within time limits
< 5 minutes RTO
High
NFR-008
Data Durability
DNS configuration data SHALL be persistent
99.99% durability
High
NFR-009
Graceful Shutdown
Service SHALL handle shutdown gracefully without data loss
100% success rate
Medium
NFR-010
High Availability
Service SHALL support primary/secondary configurations
Active-passive setup
Low
Scalability Requirements
ID
Requirement
Description
Target Value
Priority
NFR-011
Zone Capacity
The system SHALL support multiple DNS zones
100 zones minimum
High
NFR-012
Record Capacity
Each zone SHALL support DNS records
10,000 records per zone
High
NFR-013
Client Connections
The system SHALL handle concurrent client connections
500 concurrent connections
Medium
NFR-014
Memory Usage
DNS server SHALL operate within memory constraints
< 1GB RAM baseline
Medium
NFR-015
Storage Growth
The system SHALL handle storage growth gracefully
Linear growth pattern
Low
Security Requirements
ID
Requirement
Description
Target Value
Priority
NFR-016
Key Strength
TSIG keys SHALL use strong cryptographic algorithms
HMAC-SHA256 minimum
High
NFR-017
Key Length
TSIG keys SHALL meet minimum length requirements
256-bit minimum
High
NFR-018
Access Logging
All DNS update attempts SHALL be logged
100% coverage
High
NFR-019
Audit Trail
Security events SHALL be recorded for audit purposes
90-day retention
Medium
NFR-020
Vulnerability Management
System SHALL be updated for security vulnerabilities
< 30 days for critical
Medium
Operational Requirements
ID
Requirement
Description
Target Value
Priority
NFR-021
Monitoring
The system SHALL provide comprehensive monitoring metrics
95% metric coverage
High
NFR-022
Logging
All operations SHALL be logged with appropriate detail
Configurable log levels
High
NFR-023
Documentation
System SHALL provide complete operational documentation
100% API coverage
Medium
NFR-024
Backup Frequency
Configuration backups SHALL be performed regularly
Daily automated backups
Medium
NFR-025
Disaster Recovery
System SHALL support disaster recovery procedures
< 4 hour RPO
Low
Sizing Requirements
Resource Allocation
Component
Minimum
Recommended
Maximum
Notes
CPU 1 vCPU
2 vCPU
4 vCPU
Per DNS server instance
Memory 512 MB
1 GB
4 GB
Baseline + zone data
Storage 1 GB
5 GB
50 GB
Configuration + logs + backups
Network 100 Mbps
1 Gbps
10 Gbps
Depends on query volume
Capacity Planning
Metric
Small Environment
Medium Environment
Large Environment
DNS Zones 1-10 zones
11-50 zones
51-100 zones
Total Records < 1,000 records
1,000-50,000 records
50,000-500,000 records
Queries/Second < 100 QPS
100-1,000 QPS
1,000-10,000 QPS
Updates/Hour < 10 updates
10-100 updates
100-1,000 updates
Storage Growth 100 MB/year
1 GB/year
10 GB/year
Docker Container Limits
Resource
Development
Staging
Production
CPU Limit 1 CPU
2 CPU
4 CPU
Memory Limit 512 MB
1 GB
2 GB
Memory Reservation 256 MB
512 MB
1 GB
Swap Limit 1 GB
2 GB
4 GB
File Descriptors 1024
4096
8192
Network Requirements
Environment
Internal Bandwidth
External Bandwidth
Latency
Packet Loss
Development 100 Mbps
10 Mbps
< 100ms
< 1%
Staging 1 Gbps
100 Mbps
< 50ms
< 0.1%
Production 10 Gbps
1 Gbps
< 20ms
< 0.01%
Compliance Requirements
ID
Requirement
Description
Standard/Regulation
CR-001
Data Retention
DNS logs SHALL be retained per compliance requirements
SOX, GDPR
CR-002
Audit Logging
All administrative actions SHALL be audited
SOX, PCI-DSS
CR-003
Access Control
Role-based access SHALL be implemented
ISO 27001
CR-004
Encryption
Data in transit SHALL be encrypted
TLS 1.2+
CR-005
Key Management
Cryptographic keys SHALL be managed securely
FIPS 140-2
Response Time Targets
Query Type
Target Response Time
Measurement Method
A Record < 5ms
95th percentile
AAAA Record < 5ms
95th percentile
MX Record < 10ms
95th percentile
TXT Record < 15ms
95th percentile
Zone Transfer < 1s/10K records
Average time
Throughput Requirements
Operation
Target Throughput
Concurrency Level
DNS Queries 1,000 QPS
500 concurrent
Dynamic Updates 100 UPS
50 concurrent
Zone Transfers 10 concurrent
N/A
TSIG Operations 500 OPS
100 concurrent
This requirements specification provides the foundation for system design, testing, and operational planning of the BIND DNS server deployment.