DNS, DHCP and IP address management (DDI) sit underneath every connection your organisation makes, yet many teams still run them from spreadsheets, scattered Windows servers and cloud consoles nobody reconciles. A DDI platform brings the three services under one data model, one set of admin roles and one API. Buying one is also a security decision: the platform becomes the place where you enforce DNS response policy, sign zones, see which device asked for which address, and hand automation the right to change records. This vendor-neutral buyer's guide is for network, infrastructure and security architects replacing native Windows DNS and DHCP or consolidating several tools. It covers requirements, the capability areas that matter, evaluation criteria, vendor questions, red flags and a proof of concept plan.
Key takeaways
- Start from the inventory you cannot produce today. The strongest case for DDI is an authoritative record of subnets, leases, records and owners that security tools can query. Score discovery and data quality first.
- Treat DNS security features as policy engines, not tick boxes. Ask how response policy zones (RPZ), threat feeds and DNSSEC validation are managed, logged and rolled back, not just whether they exist.
- The API is an identity problem. Automation, IPAM sync and cloud connectors all hold credentials that can rewrite DNS. Require scoped, per-integration tokens and full audit of every change.
- High availability must be tested, not described. Fail a grid member, a DHCP failover partner and the management appliance during the proof of concept and time recovery.
- Licensing shapes architecture. Per-appliance, per-IP, per-query and subscription models push you towards different designs. Model three years of growth before you compare prices.
Define requirements
Write these down with network, security operations, cloud and identity teams before any vendor meeting. NIST SP 800-81 Rev. 3 (Secure DNS Deployment Guide, final March 2026) is a good structure for the DNS half: it treats DNS as both critical infrastructure and a security control within zero trust. See the NIST SP 800-81 Rev. 3 Guide.
- Estate: number of sites, subnets (IPv4 and IPv6), DHCP scopes, active leases, zones and records; peak recursive queries per second at each site.
- Current state: Microsoft DNS and DHCP on domain controllers, BIND or other open source servers, cloud-native DNS, spreadsheets. Note which must remain (for example Active Directory integrated zones) and which you will retire. The Windows Server DNS and DHCP Security Guide covers hardening what stays.
- Roles: internal recursive resolvers, internal authoritative, external authoritative, DHCP, IPAM only. Some organisations buy IPAM and DHCP but keep external DNS with a managed provider.
- Security outcomes: block known-bad domains at the resolver, validate DNSSEC, sign your own zones, log every query with the client identity, detect rogue devices and tunnelling.
- Cloud: which public cloud DNS services and private zones must be discovered or synchronised, and in which direction.
- Automation: which systems will create records and reserve addresses (provisioning pipelines, infrastructure as code, IT service management) and with what approval.
- Compliance: retention of DNS and DHCP logs for investigations, change evidence for audit, data residency for any cloud-hosted management plane.
Capability areas
| Area | What good looks like | Why security cares |
|---|---|---|
| DNS firewall and RPZ | Response policy zones with all trigger types (QNAME, response IP, NSDNAME, NSIP, client IP) and actions (NXDOMAIN, NODATA, PASSTHRU, DROP, local data redirect); multiple feeds with precedence; RPZ distributed by IXFR with TSIG | Stops resolution of malicious and newly registered domains for every device, including unmanaged ones. See the Protective DNS Guide. |
| DNSSEC | Validation on recursive resolvers; automated signing, key rollover and DS record handling for authoritative zones | Origin authentication of DNS data (RFC 9364). Manual key rollovers are a common cause of outages. See the DNSSEC Deployment Guide. |
| Query and response logging | Every query with client IP, MAC or lease identity, response, policy hit; streaming export to SIEM in a documented schema | DNS logs are often the first evidence of command and control. See the DNS Logging and Detection Guide. |
| Encrypted DNS | DNS over TLS and DNS over HTTPS service for managed clients; ability to block or steer external encrypted resolvers | Keeps policy in force when browsers and apps try to bypass the corporate resolver. See the Encrypted DNS Enterprise Guide. |
| DHCP fingerprinting | Device classification from options 55 (Parameter Request List), 60 (Vendor class identifier) and 61 (Client-identifier); alerts on unknown or changed device types; feed to NAC | Finds rogue and unmanaged devices at the moment they join. See the DHCP Security Guide. |
| IPAM and discovery | Subnet and address inventory from DHCP, DNS, network scans, switch and router tables, and cloud APIs; conflict detection; owner and site metadata | Asset inventory is the base of CIS Control 1 and of incident scoping. |
| Cloud DNS integration | Discovery and two-way sync of public cloud zones, private zones and VPC address space; conditional forwarding design | Shadow zones and dangling records in cloud accounts lead to subdomain takeover. See the Subdomain Takeover and Dangling DNS Guide. |
| Admin and API control | Role based admin scoped by zone, network view and object type; SSO with MFA; per-integration API tokens; change approval workflows; full audit trail | DNS changes can redirect mail, web and authentication traffic. See the Authoritative DNS and Registrar Account Security Guide. |
| High availability | Anycast or multiple resolvers per site, DHCP failover or split scopes, management plane redundancy, documented behaviour when the grid master is lost | DNS and DHCP outages stop everything, including security tooling. |
Evaluation criteria
| Criterion | Weight (suggested) | How to score it |
|---|---|---|
| Inventory accuracy and discovery coverage | 20% | Percentage of known subnets and devices found in the proof of concept versus your trusted list; time to detect a new subnet |
| DNS security policy (RPZ, feeds, DNSSEC) | 20% | Trigger and action coverage; time to push a block to all resolvers; ease of exception handling and rollback |
| Logging and SIEM integration | 15% | Fields per query, client attribution to a device or user, export latency, cost of retention |
| API, automation and admin security | 15% | API coverage of all objects; token scoping and expiry; RBAC granularity; audit completeness; SSO and MFA for the console |
| Resilience and performance | 15% | Measured failover times; queries per second under load with RPZ enabled; upgrade without outage |
| Cloud and hybrid fit | 10% | Clouds supported today; sync direction; conflict handling between cloud and on-premises records |
| Commercial model | 5% | Three-year cost at projected growth; cost of feeds, logging and HA members; exit and data export terms |
Adjust weights to your situation. A small organisation replacing Windows DNS and DHCP at a few sites should weight ease of operation and cost higher; a large or regulated organisation should weight logging, RBAC and resilience higher.
Questions to ask vendors
- Which RPZ trigger types and actions do your resolvers support, and how do you order multiple policy zones and feeds? Show a block, an exception and a rollback.
- How are RPZ and threat feed updates delivered to every resolver, and are zone transfers authenticated with TSIG (RFC 8945)?
- How do you automate DNSSEC key rollovers and DS record updates at the parent, and what alerts fire before a signature expires?
- What does one query log record contain? Can you attribute a query to a DHCP lease, MAC address and, where integrated, a user?
- Which DHCP options do you use for fingerprinting, how often is the fingerprint database updated, and can classifications be exported to our NAC?
- How do API tokens work: can each integration have its own token limited to specific zones, networks and operations, with expiry? Are tokens stored hashed?
- Is the console available with our identity provider through SAML or OIDC, with MFA enforced and local accounts limited to break-glass?
- Which cloud DNS services can you discover and synchronise today, not on the roadmap, and in which direction?
- What happens to DNS resolution and DHCP leasing if the central management node is unreachable for 24 hours?
- How do you migrate existing Microsoft DNS, including Active Directory integrated zones and secure dynamic updates?
- What is the licensing unit (appliance, IP address, query volume, subscription tier), and which security features cost extra?
Red flags
- A single shared API account for all integrations, or tokens that cannot be scoped or expired.
- DNS security that only works when traffic is sent to the vendor's cloud resolver, with no on-premises enforcement option where you need it.
- Query logging described as available but too expensive or too slow to enable at full volume.
- DNSSEC signing that requires manual key rollovers.
- Discovery that cannot read cloud accounts, or reads them only once at import.
- High availability claims with no documented failover times or behaviour when the management node is lost.
- No export of your full IPAM data in an open format, which locks you in.
Proof of concept
- Load real data: import a copy of your current DNS zones, DHCP scopes and address spreadsheets for at least one large site and one cloud account. Compare discovered objects against your trusted inventory.
- Test DNS policy: subscribe to a test RPZ, block a test domain, add a per-client exception and roll back. Time propagation to every resolver.
- Validate DNSSEC: sign a test zone, run a key rollover and confirm validation of a deliberately broken signed domain fails safely.
- Check attribution: generate queries from a known laptop and trace them in your SIEM to lease, MAC and device type.
- Probe the API: create a scoped token for a pipeline, try to change a record outside its scope and confirm it is refused and logged.
- Break things: stop a resolver, a DHCP failover partner and the management node. Measure client impact and recovery time.
- Load test: run peak query rates with RPZ and logging enabled and record latency.
- Plan the exit: export all data and confirm it can be re-imported elsewhere.
Standards and references
- NIST: SP 800-81 Rev. 3 Secure Domain Name System (DNS) Deployment Guide
- IETF: RFC 9364 DNS Security Extensions (DNSSEC)
- IETF: RFC 8945 Secret Key Transaction Authentication for DNS (TSIG)
- IETF: draft-vixie-dnsop-dns-rpz DNS Response Policy Zones (expired Internet-Draft)
- IETF: RFC 2132 DHCP Options and BOOTP Vendor Extensions
- CISA: Protective Domain Name System Resolver
How NHI Mgmt Group can help
We provide independent requirements, RFP and evaluation support. Browse vendors in our products directory or contact us.
Related NHI Mgmt Group resources: DNS Security Guide · Windows Server DNS and DHCP Security Guide · Protective DNS Guide · Network Access Control (NAC) Guide