What is a DNS log?¶

A DNS log records requests and responses involved in translating names, such as website domains, into network addresses.

It can help show that a device, account or network asked a DNS service about a particular domain at a particular time.

Avoid this assumption: That a DNS query proves the user deliberately visited the website named in the request. It does not.

DNS activity can be generated by browsers, applications, email clients, operating systems, adverts, background services, security software and malware. A query may occur because content was embedded in another page, because an application checked for updates or because a cached record expired.

A DNS log may include the requested name, query type, response, source address, resolver, client identifier and timestamp. This can be valuable for establishing that a system attempted to resolve a domain and for identifying patterns across devices or time.

But a query does not prove that a connection followed, that content was downloaded or that a person saw anything. Cached DNS information may allow later connections without a new query. Encrypted DNS, VPNs, local resolvers and external DNS services may also bypass the logging point being examined.

Investigators should identify which resolver created the record and whether it served the relevant device at the time. Ask whether the source field contains an end-device address, a forwarded request or a shared network address. Establish retention, time zone, query logging settings and whether responses were recorded.

Preserve the original DNS data and surrounding entries. Correlate important queries with proxy, firewall, endpoint, browser, VPN and server records. Where attribution matters, link the source device or account through DHCP, authentication and device evidence.

Operational takeaway¶

A DNS log can show that a name-resolution request was observed, but it does not by itself prove a deliberate visit, successful connection, content access or personal responsibility.