Running simple JNDI application with DNS context lookup done from virtual thread and the -Djdk.tracePinnedThreads=full system property set yields the following trace output:
Thread[#21,ForkJoinPool-1-worker-1,5,CarrierThreads]
    java.base/java.lang.VirtualThread$VThreadContinuation.onPinned(VirtualThread.java:180)
    java.base/jdk.internal.vm.Continuation.onPinned0(Continuation.java:398)
    java.base/jdk.internal.vm.Continuation.yield0(Continuation.java:390)
    java.base/jdk.internal.vm.Continuation.yield(Continuation.java:357)
    java.base/java.lang.VirtualThread.yieldContinuation(VirtualThread.java:370)
    java.base/java.lang.VirtualThread.parkNanos(VirtualThread.java:532)
    java.base/java.lang.System$2.parkVirtualThread(System.java:2605)
    java.base/jdk.internal.misc.VirtualThreads.park(VirtualThreads.java:67)
    java.base/java.util.concurrent.locks.LockSupport.parkNanos(LockSupport.java:408)
    java.base/sun.nio.ch.Poller.poll2(Poller.java:137)
    java.base/sun.nio.ch.Poller.poll(Poller.java:102)
    java.base/sun.nio.ch.Poller.poll(Poller.java:87)
    java.base/sun.nio.ch.DatagramChannelImpl.park(DatagramChannelImpl.java:486)
    java.base/sun.nio.ch.DatagramChannelImpl.trustedBlockingReceive(DatagramChannelImpl.java:734)
    java.base/sun.nio.ch.DatagramChannelImpl.blockingReceive(DatagramChannelImpl.java:661)
    java.base/sun.nio.ch.DatagramSocketAdaptor.receive(DatagramSocketAdaptor.java:241) <== monitors:1
    java.base/java.net.DatagramSocket.receive(DatagramSocket.java:714)
    jdk.naming.dns/com.sun.jndi.dns.DnsClient.doUdpQuery(DnsClient.java:430) <== monitors:1
    jdk.naming.dns/com.sun.jndi.dns.DnsClient.query(DnsClient.java:216)
    jdk.naming.dns/com.sun.jndi.dns.Resolver.query(Resolver.java:81)
    jdk.naming.dns/com.sun.jndi.dns.DnsContext.c_lookup(DnsContext.java:290)
    java.naming/com.sun.jndi.toolkit.ctx.ComponentContext.p_lookup(ComponentContext.java:542)
    java.naming/com.sun.jndi.toolkit.ctx.PartialCompositeContext.lookup(PartialCompositeContext.java:177)
    java.naming/com.sun.jndi.toolkit.ctx.PartialCompositeContext.lookup(PartialCompositeContext.java:166)
    java.naming/javax.naming.InitialContext.lookup(InitialContext.java:409)
    DnsWithVTs.doLookup(DnsWithVTs.java:26)
    DnsWithVTs.lambda$doDnsCtxLookup$0(DnsWithVTs.java:15)
    java.base/java.lang.VirtualThread.run(VirtualThread.java:287)
    java.base/java.lang.VirtualThread$VThreadContinuation.lambda$new$0(VirtualThread.java:174)
    java.base/jdk.internal.vm.Continuation.enter0(Continuation.java:327)
    java.base/jdk.internal.vm.Continuation.enter(Continuation.java:320)

com.sun.jndi.dns.DnsClient class needs to be updated to use DatagramChannel and j.u.c.l locks to be virtual thread friendly by avoiding pinning carrier threads.